Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6

24 files changed, 440 insertions, 188 deletions

diff --git a/arch/um/Makefile b/arch/um/Makefile
index c8016a98483..5d5ed726faa 100644
--- a/arch/um/Makefile
+++ b/arch/um/Makefile
@@ -64,9 +64,14 @@ CFLAGS += $(CFLAGS-y) -D__arch_um__ -DSUBARCH=\"$(SUBARCH)\"	\
 
 AFLAGS += $(ARCH_INCLUDE)
 
-USER_CFLAGS := $(patsubst -I%,,$(CFLAGS))
-USER_CFLAGS := $(patsubst -D__KERNEL__,,$(USER_CFLAGS)) $(ARCH_INCLUDE) \
-	$(MODE_INCLUDE) -D_FILE_OFFSET_BITS=64
+USER_CFLAGS = $(patsubst $(KERNEL_DEFINES),,$(patsubst -D__KERNEL__,,\
+	$(patsubst -I%,,$(CFLAGS)))) $(ARCH_INCLUDE) $(MODE_INCLUDE) \
+	-D_FILE_OFFSET_BITS=64
+
+include $(srctree)/$(ARCH_DIR)/Makefile-$(SUBARCH)
+
+#This will adjust *FLAGS accordingly to the platform.
+include $(srctree)/$(ARCH_DIR)/Makefile-os-$(OS)
 
 # -Derrno=kernel_errno - This turns all kernel references to errno into
 # kernel_errno to separate them from the libc errno.  This allows -fno-common
@@ -74,15 +79,11 @@ USER_CFLAGS := $(patsubst -D__KERNEL__,,$(USER_CFLAGS)) $(ARCH_INCLUDE) \
 # errnos.
 # These apply to kernelspace only.
 
-CFLAGS += -Derrno=kernel_errno -Dsigprocmask=kernel_sigprocmask \
-	-Dmktime=kernel_mktime
+KERNEL_DEFINES = -Derrno=kernel_errno -Dsigprocmask=kernel_sigprocmask \
+	-Dmktime=kernel_mktime $(ARCH_KERNEL_DEFINES)
+CFLAGS += $(KERNEL_DEFINES)
 CFLAGS += $(call cc-option,-fno-unit-at-a-time,)
 
-include $(srctree)/$(ARCH_DIR)/Makefile-$(SUBARCH)
-
-#This will adjust *FLAGS accordingly to the platform.
-include $(srctree)/$(ARCH_DIR)/Makefile-os-$(OS)
-
 # These are needed for clean and mrproper, since in that case .config is not
 # included; the values here are meaningless
 
diff --git a/arch/um/Makefile-i386 b/arch/um/Makefile-i386
index b65ca115ef7..c9f1c5b24c9 100644
--- a/arch/um/Makefile-i386
+++ b/arch/um/Makefile-i386
@@ -16,7 +16,6 @@ OBJCOPYFLAGS  		:= -O binary -R .note -R .comment -S
 ifeq ("$(origin SUBARCH)", "command line")
 ifneq ("$(shell uname -m | sed -e s/i.86/i386/)", "$(SUBARCH)")
 CFLAGS			+= $(call cc-option,-m32)
-USER_CFLAGS		+= $(call cc-option,-m32)
 AFLAGS			+= $(call cc-option,-m32)
 LINK-y			+= $(call cc-option,-m32)
 UML_OBJCOPYFLAGS	+= -F $(ELF_FORMAT)
@@ -25,7 +24,7 @@ export LDFLAGS HOSTCFLAGS HOSTLDFLAGS UML_OBJCOPYFLAGS
 endif
 endif
 
-CFLAGS += -U__$(SUBARCH)__ -U$(SUBARCH)
+ARCH_KERNEL_DEFINES += -U__$(SUBARCH)__ -U$(SUBARCH)
 
 # First of all, tune CFLAGS for the specific CPU. This actually sets cflags-y.
 include $(srctree)/arch/i386/Makefile.cpu
@@ -38,4 +37,3 @@ cflags-y += $(call cc-option,-mpreferred-stack-boundary=2)
 cflags-y += -ffreestanding
 
 CFLAGS += $(cflags-y)
-USER_CFLAGS += $(cflags-y)
diff --git a/arch/um/Makefile-x86_64 b/arch/um/Makefile-x86_64
index d278682dd79..69ecea63fda 100644
--- a/arch/um/Makefile-x86_64
+++ b/arch/um/Makefile-x86_64
@@ -8,8 +8,8 @@ _extra_flags_ = -fno-builtin -m64
 
 #We #undef __x86_64__ for kernelspace, not for userspace where
 #it's needed for headers to work!
-CFLAGS += -U__$(SUBARCH)__ $(_extra_flags_)
-USER_CFLAGS += $(_extra_flags_)
+ARCH_KERNEL_DEFINES = -U__$(SUBARCH)__
+CFLAGS += $(_extra_flags_)
 
 CHECKFLAGS  += -m64
 AFLAGS += -m64
diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c
index d08bd036ccb..7b172160fe0 100644
--- a/arch/um/drivers/mconsole_kern.c
+++ b/arch/um/drivers/mconsole_kern.c
@@ -79,7 +79,7 @@ static irqreturn_t mconsole_interrupt(int irq, void *dev_id)
 	/* long to avoid size mismatch warnings from gcc */
 	long fd;
 	struct mconsole_entry *new;
-	struct mc_request req;
+	static struct mc_request req;	/* that's OK */
 
 	fd = (long) dev_id;
 	while (mconsole_get_request(fd, &req)){
@@ -91,6 +91,7 @@ static irqreturn_t mconsole_interrupt(int irq, void *dev_id)
 				mconsole_reply(&req, "Out of memory", 1, 0);
 			else {
 				new->request = req;
+				new->request.regs = get_irq_regs()->regs;
 				list_add(&new->list, &mc_requests);
 			}
 		}
@@ -314,9 +315,21 @@ void mconsole_stop(struct mc_request *req)
 {
 	deactivate_fd(req->originating_fd, MCONSOLE_IRQ);
 	os_set_fd_block(req->originating_fd, 1);
-	mconsole_reply(req, "", 0, 0);
-	while(mconsole_get_request(req->originating_fd, req)){
-		if(req->cmd->handler == mconsole_go) break;
+	mconsole_reply(req, "stopped", 0, 0);
+	while (mconsole_get_request(req->originating_fd, req)) {
+		if (req->cmd->handler == mconsole_go)
+			break;
+		if (req->cmd->handler == mconsole_stop) {
+			mconsole_reply(req, "Already stopped", 1, 0);
+			continue;
+		}
+		if (req->cmd->handler == mconsole_sysrq) {
+			struct pt_regs *old_regs;
+			old_regs = set_irq_regs((struct pt_regs *)&req->regs);
+			mconsole_sysrq(req);
+			set_irq_regs(old_regs);
+			continue;
+		}
 		(*req->cmd->handler)(req);
 	}
 	os_set_fd_block(req->originating_fd, 0);
@@ -673,9 +686,7 @@ static void with_console(struct mc_request *req, void (*proc)(void *),
 static void sysrq_proc(void *arg)
 {
 	char *op = arg;
-	struct pt_regs *old_regs = set_irq_regs(&current->thread.regs);
 	handle_sysrq(*op, NULL);
-	set_irq_regs(old_regs);
 }
 
 void mconsole_sysrq(struct mc_request *req)
diff --git a/arch/um/drivers/mconsole_user.c b/arch/um/drivers/mconsole_user.c
index 17068eb746c..75aef6f7ef6 100644
--- a/arch/um/drivers/mconsole_user.c
+++ b/arch/um/drivers/mconsole_user.c
@@ -14,6 +14,7 @@
 #include <sys/un.h>
 #include <unistd.h>
 #include "user.h"
+#include "sysdep/ptrace.h"
 #include "mconsole.h"
 #include "umid.h"
 #include "user_util.h"
diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index bc458f57921..49c047b75cc 100644
--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -106,10 +106,15 @@ static inline void ubd_set_bit(__u64 bit, unsigned char *data)
 
 #define DRIVER_NAME "uml-blkdev"
 
+/* Can be taken in interrupt context, and is passed to the block layer to lock
+ * the request queue. Kernel side code knows that. */
 static DEFINE_SPINLOCK(ubd_io_lock);
-static DEFINE_SPINLOCK(ubd_lock);
 
-static void (*do_ubd)(void);
+static DEFINE_MUTEX(ubd_lock);
+
+/* XXX - this made sense in 2.4 days, now it's only used as a boolean, and
+ * probably it doesn't make sense even for that. */
+static int do_ubd;
 
 static int ubd_open(struct inode * inode, struct file * filp);
 static int ubd_release(struct inode * inode, struct file * file);
@@ -117,7 +122,7 @@ static int ubd_ioctl(struct inode * inode, struct file * file,
 		     unsigned int cmd, unsigned long arg);
 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo);
 
-#define MAX_DEV (8)
+#define MAX_DEV (16)
 
 static struct block_device_operations ubd_blops = {
         .owner		= THIS_MODULE,
@@ -150,8 +155,9 @@ static struct gendisk *fake_gendisk[MAX_DEV];
 static struct openflags global_openflags = OPEN_FLAGS;
 
 struct cow {
-	/* This is the backing file, actually */
+	/* backing file name */
 	char *file;
+	/* backing file fd */
 	int fd;
 	unsigned long *bitmap;
 	unsigned long bitmap_len;
@@ -160,14 +166,16 @@ struct cow {
 };
 
 struct ubd {
+	/* name (and fd, below) of the file opened for writing, either the
+	 * backing or the cow file. */
 	char *file;
 	int count;
 	int fd;
 	__u64 size;
 	struct openflags boot_openflags;
 	struct openflags openflags;
-	int shared;
-	int no_cow;
+	unsigned shared:1;
+	unsigned no_cow:1;
 	struct cow cow;
 	struct platform_device pdev;
 };
@@ -192,18 +200,7 @@ struct ubd {
         .cow =			DEFAULT_COW, \
 }
 
-struct ubd ubd_dev[MAX_DEV] = { [ 0 ... MAX_DEV - 1 ] = DEFAULT_UBD };
-
-static int ubd0_init(void)
-{
-	struct ubd *dev = &ubd_dev[0];
-
-	if(dev->file == NULL)
-		dev->file = "root_fs";
-	return(0);
-}
-
-__initcall(ubd0_init);
+struct ubd ubd_devs[MAX_DEV] = { [ 0 ... MAX_DEV - 1 ] = DEFAULT_UBD };
 
 /* Only changed by fake_ide_setup which is a setup */
 static int fake_ide = 0;
@@ -277,7 +274,7 @@ static int parse_unit(char **ptr)
 			return(-1);
 		*ptr = end;
 	}
-	else if (('a' <= *str) && (*str <= 'h')) {
+	else if (('a' <= *str) && (*str <= 'z')) {
 		n = *str - 'a';
 		str++;
 		*ptr = str;
@@ -285,9 +282,13 @@ static int parse_unit(char **ptr)
 	return(n);
 }
 
+/* If *index_out == -1 at exit, the passed option was a general one;
+ * otherwise, the str pointer is used (and owned) inside ubd_devs array, so it
+ * should not be freed on exit.
+ */
 static int ubd_setup_common(char *str, int *index_out)
 {
-	struct ubd *dev;
+	struct ubd *ubd_dev;
 	struct openflags flags = global_openflags;
 	char *backing_file;
 	int n, err, i;
@@ -311,7 +312,7 @@ static int ubd_setup_common(char *str, int *index_out)
 		}
 
 		err = 1;
- 		spin_lock(&ubd_lock);
+ 		mutex_lock(&ubd_lock);
  		if(fake_major != MAJOR_NR){
  			printk(KERN_ERR "Can't assign a fake major twice\n");
  			goto out1;
@@ -323,7 +324,7 @@ static int ubd_setup_common(char *str, int *index_out)
 		       major);
  		err = 0;
  	out1:
- 		spin_unlock(&ubd_lock);
+ 		mutex_unlock(&ubd_lock);
 		return(err);
 	}
 
@@ -340,10 +341,10 @@ static int ubd_setup_common(char *str, int *index_out)
 	}
 
 	err = 1;
-	spin_lock(&ubd_lock);
+	mutex_lock(&ubd_lock);
 
-	dev = &ubd_dev[n];
-	if(dev->file != NULL){
+	ubd_dev = &ubd_devs[n];
+	if(ubd_dev->file != NULL){
 		printk(KERN_ERR "ubd_setup : device already configured\n");
 		goto out;
 	}
@@ -360,10 +361,10 @@ static int ubd_setup_common(char *str, int *index_out)
 			flags.s = 1;
 			break;
 		case 'd':
-			dev->no_cow = 1;
+			ubd_dev->no_cow = 1;
 			break;
 		case 'c':
-			dev->shared = 1;
+			ubd_dev->shared = 1;
 			break;
 		case '=':
 			str++;
@@ -390,7 +391,7 @@ break_loop:
 	}
 
 	if(backing_file){
-		if(dev->no_cow)
+		if(ubd_dev->no_cow)
 			printk(KERN_ERR "Can't specify both 'd' and a "
 			       "cow file\n");
 		else {
@@ -398,11 +399,11 @@ break_loop:
 			backing_file++;
 		}
 	}
-	dev->file = str;
-	dev->cow.file = backing_file;
-	dev->boot_openflags = flags;
+	ubd_dev->file = str;
+	ubd_dev->cow.file = backing_file;
+	ubd_dev->boot_openflags = flags;
 out:
-	spin_unlock(&ubd_lock);
+	mutex_unlock(&ubd_lock);
 	return(err);
 }
 
@@ -472,8 +473,9 @@ int thread_fd = -1;
 
 /* Changed by ubd_handler, which is serialized because interrupts only
  * happen on CPU 0.
+ * XXX: currently unused.
  */
-int intr_count = 0;
+static int intr_count = 0;
 
 /* call ubd_finish if you need to serialize */
 static void __ubd_finish(struct request *req, int error)
@@ -493,6 +495,8 @@ static void __ubd_finish(struct request *req, int error)
 	end_request(req, 1);
 }
 
+/* Callable only from interrupt context - otherwise you need to do
+ * spin_lock_irq()/spin_lock_irqsave() */
 static inline void ubd_finish(struct request *req, int error)
 {
  	spin_lock(&ubd_io_lock);
@@ -500,14 +504,15 @@ static inline void ubd_finish(struct request *req, int error)
 	spin_unlock(&ubd_io_lock);
 }
 
-/* Called without ubd_io_lock held */
+/* XXX - move this inside ubd_intr. */
+/* Called without ubd_io_lock held, and only in interrupt context. */
 static void ubd_handler(void)
 {
 	struct io_thread_req req;
 	struct request *rq = elv_next_request(ubd_queue);
 	int n;
 
-	do_ubd = NULL;
+	do_ubd = 0;
 	intr_count++;
 	n = os_read_file(thread_fd, &req, sizeof(req));
 	if(n != sizeof(req)){
@@ -521,7 +526,9 @@ static void ubd_handler(void)
 
 	ubd_finish(rq, req.error);
 	reactivate_fd(thread_fd, UBD_IRQ);	
+	spin_lock(&ubd_io_lock);
 	do_ubd_request(ubd_queue);
+	spin_unlock(&ubd_io_lock);
 }
 
 static irqreturn_t ubd_intr(int irq, void *dev)
@@ -541,87 +548,90 @@ void kill_io_thread(void)
 
 __uml_exitcall(kill_io_thread);
 
-static int ubd_file_size(struct ubd *dev, __u64 *size_out)
+static inline int ubd_file_size(struct ubd *ubd_dev, __u64 *size_out)
 {
 	char *file;
 
-	file = dev->cow.file ? dev->cow.file : dev->file;
+	file = ubd_dev->cow.file ? ubd_dev->cow.file : ubd_dev->file;
 	return(os_file_size(file, size_out));
 }
 
-static void ubd_close(struct ubd *dev)
+static void ubd_close_dev(struct ubd *ubd_dev)
 {
-	os_close_file(dev->fd);
-	if(dev->cow.file == NULL)
+	os_close_file(ubd_dev->fd);
+	if(ubd_dev->cow.file == NULL)
 		return;
 
-	os_close_file(dev->cow.fd);
-	vfree(dev->cow.bitmap);
-	dev->cow.bitmap = NULL;
+	os_close_file(ubd_dev->cow.fd);
+	vfree(ubd_dev->cow.bitmap);
+	ubd_dev->cow.bitmap = NULL;
 }
 
-static int ubd_open_dev(struct ubd *dev)
+static int ubd_open_dev(struct ubd *ubd_dev)
 {
 	struct openflags flags;
 	char **back_ptr;
 	int err, create_cow, *create_ptr;
+	int fd;
 
-	dev->openflags = dev->boot_openflags;
+	ubd_dev->openflags = ubd_dev->boot_openflags;
 	create_cow = 0;
-	create_ptr = (dev->cow.file != NULL) ? &create_cow : NULL;
-	back_ptr = dev->no_cow ? NULL : &dev->cow.file;
-	dev->fd = open_ubd_file(dev->file, &dev->openflags, dev->shared,
-				back_ptr, &dev->cow.bitmap_offset,
-				&dev->cow.bitmap_len, &dev->cow.data_offset,
+	create_ptr = (ubd_dev->cow.file != NULL) ? &create_cow : NULL;
+	back_ptr = ubd_dev->no_cow ? NULL : &ubd_dev->cow.file;
+
+	fd = open_ubd_file(ubd_dev->file, &ubd_dev->openflags, ubd_dev->shared,
+				back_ptr, &ubd_dev->cow.bitmap_offset,
+				&ubd_dev->cow.bitmap_len, &ubd_dev->cow.data_offset,
 				create_ptr);
 
-	if((dev->fd == -ENOENT) && create_cow){
-		dev->fd = create_cow_file(dev->file, dev->cow.file,
-					  dev->openflags, 1 << 9, PAGE_SIZE,
-					  &dev->cow.bitmap_offset,
-					  &dev->cow.bitmap_len,
-					  &dev->cow.data_offset);
-		if(dev->fd >= 0){
+	if((fd == -ENOENT) && create_cow){
+		fd = create_cow_file(ubd_dev->file, ubd_dev->cow.file,
+					  ubd_dev->openflags, 1 << 9, PAGE_SIZE,
+					  &ubd_dev->cow.bitmap_offset,
+					  &ubd_dev->cow.bitmap_len,
+					  &ubd_dev->cow.data_offset);
+		if(fd >= 0){
 			printk(KERN_INFO "Creating \"%s\" as COW file for "
-			       "\"%s\"\n", dev->file, dev->cow.file);
+			       "\"%s\"\n", ubd_dev->file, ubd_dev->cow.file);
 		}
 	}
 
-	if(dev->fd < 0){
-		printk("Failed to open '%s', errno = %d\n", dev->file,
-		       -dev->fd);
-		return(dev->fd);
+	if(fd < 0){
+		printk("Failed to open '%s', errno = %d\n", ubd_dev->file,
+		       -fd);
+		return fd;
 	}
+	ubd_dev->fd = fd;
 
-	if(dev->cow.file != NULL){
+	if(ubd_dev->cow.file != NULL){
 		err = -ENOMEM;
-		dev->cow.bitmap = (void *) vmalloc(dev->cow.bitmap_len);
-		if(dev->cow.bitmap == NULL){
+		ubd_dev->cow.bitmap = (void *) vmalloc(ubd_dev->cow.bitmap_len);
+		if(ubd_dev->cow.bitmap == NULL){
 			printk(KERN_ERR "Failed to vmalloc COW bitmap\n");
 			goto error;
 		}
 		flush_tlb_kernel_vm();
 
-		err = read_cow_bitmap(dev->fd, dev->cow.bitmap,
-				      dev->cow.bitmap_offset,
-				      dev->cow.bitmap_len);
+		err = read_cow_bitmap(ubd_dev->fd, ubd_dev->cow.bitmap,
+				      ubd_dev->cow.bitmap_offset,
+				      ubd_dev->cow.bitmap_len);
 		if(err < 0)
 			goto error;
 
-		flags = dev->openflags;
+		flags = ubd_dev->openflags;
 		flags.w = 0;
-		err = open_ubd_file(dev->cow.file, &flags, dev->shared, NULL,
+		err = open_ubd_file(ubd_dev->cow.file, &flags, ubd_dev->shared, NULL,
 				    NULL, NULL, NULL, NULL);
 		if(err < 0) goto error;
-		dev->cow.fd = err;
+		ubd_dev->cow.fd = err;
 	}
 	return(0);
  error:
-	os_close_file(dev->fd);
+	os_close_file(ubd_dev->fd);
 	return(err);
 }
 
-static int ubd_new_disk(int major, u64 size, int unit,
+static int ubd_disk_register(int major, u64 size, int unit,
 			struct gendisk **disk_out)
 			
 {
@@ -642,13 +652,13 @@ static int ubd_new_disk(int major, u64 size, int unit,
 
 	/* sysfs register (not for ide fake devices) */
 	if (major == MAJOR_NR) {
-		ubd_dev[unit].pdev.id   = unit;
-		ubd_dev[unit].pdev.name = DRIVER_NAME;
-		platform_device_register(&ubd_dev[unit].pdev);
-		disk->driverfs_dev = &ubd_dev[unit].pdev.dev;
+		ubd_devs[unit].pdev.id   = unit;
+		ubd_devs[unit].pdev.name = DRIVER_NAME;
+		platform_device_register(&ubd_devs[unit].pdev);
+		disk->driverfs_dev = &ubd_devs[unit].pdev.dev;
 	}
 
-	disk->private_data = &ubd_dev[unit];
+	disk->private_data = &ubd_devs[unit];
 	disk->queue = ubd_queue;
 	add_disk(disk);
 
@@ -660,25 +670,25 @@ static int ubd_new_disk(int major, u64 size, int unit,
 
 static int ubd_add(int n)
 {
-	struct ubd *dev = &ubd_dev[n];
+	struct ubd *ubd_dev = &ubd_devs[n];
 	int err;
 
 	err = -ENODEV;
-	if(dev->file == NULL)
+	if(ubd_dev->file == NULL)
 		goto out;
 
-	err = ubd_file_size(dev, &dev->size);
+	err = ubd_file_size(ubd_dev, &ubd_dev->size);
 	if(err < 0)
 		goto out;
 
-	dev->size = ROUND_BLOCK(dev->size);
+	ubd_dev->size = ROUND_BLOCK(ubd_dev->size);
 
-	err = ubd_new_disk(MAJOR_NR, dev->size, n, &ubd_gendisk[n]);
+	err = ubd_disk_register(MAJOR_NR, ubd_dev->size, n, &ubd_gendisk[n]);
 	if(err)
 		goto out;
 
 	if(fake_major != MAJOR_NR)
-		ubd_new_disk(fake_major, dev->size, n,
+		ubd_disk_register(fake_major, ubd_dev->size, n,
 			     &fake_gendisk[n]);
 
 	/* perhaps this should also be under the "if (fake_major)" above */
@@ -693,32 +703,41 @@ out:
 
 static int ubd_config(char *str)
 {
-	int n, err;
+	int n, ret;
 
 	str = kstrdup(str, GFP_KERNEL);
-	if(str == NULL){
+	if (str == NULL) {
 		printk(KERN_ERR "ubd_config failed to strdup string\n");
-		return(1);
+		ret = 1;
+		goto out;
 	}
-	err = ubd_setup_common(str, &n);
-	if(err){
-		kfree(str);
-		return(-1);
+	ret = ubd_setup_common(str, &n);
+	if (ret) {
+		ret = -1;
+		goto err_free;
+	}
+	if (n == -1) {
+		ret = 0;
+		goto err_free;
 	}
-	if(n == -1) return(0);
 
- 	spin_lock(&ubd_lock);
-	err = ubd_add(n);
-	if(err)
-		ubd_dev[n].file = NULL;
- 	spin_unlock(&ubd_lock);
+ 	mutex_lock(&ubd_lock);
+	ret = ubd_add(n);
+	if (ret)
+		ubd_devs[n].file = NULL;
+ 	mutex_unlock(&ubd_lock);
 
-	return(err);
+out:
+ 	return ret;
+
+err_free:
+	kfree(str);
+	goto out;
 }
 
 static int ubd_get_config(char *name, char *str, int size, char **error_out)
 {
-	struct ubd *dev;
+	struct ubd *ubd_dev;
 	int n, len = 0;
 
 	n = parse_unit(&name);
@@ -727,24 +746,24 @@ static int ubd_get_config(char *name, char *str, int size, char **error_out)
 		return(-1);
 	}
 
-	dev = &ubd_dev[n];
-	spin_lock(&ubd_lock);
+	ubd_dev = &ubd_devs[n];
+	mutex_lock(&ubd_lock);
 
-	if(dev->file == NULL){
+	if(ubd_dev->file == NULL){
 		CONFIG_CHUNK(str, size, len, "", 1);
 		goto out;
 	}
 
-	CONFIG_CHUNK(str, size, len, dev->file, 0);
+	CONFIG_CHUNK(str, size, len, ubd_dev->file, 0);
 
-	if(dev->cow.file != NULL){
+	if(ubd_dev->cow.file != NULL){
 		CONFIG_CHUNK(str, size, len, ",", 0);
-		CONFIG_CHUNK(str, size, len, dev->cow.file, 1);
+		CONFIG_CHUNK(str, size, len, ubd_dev->cow.file, 1);
 	}
 	else CONFIG_CHUNK(str, size, len, "", 1);
 
  out:
-	spin_unlock(&ubd_lock);
+	mutex_unlock(&ubd_lock);
 	return(len);
 }
 
@@ -760,22 +779,22 @@ static int ubd_id(char **str, int *start_out, int *end_out)
 
 static int ubd_remove(int n)
 {
-	struct ubd *dev;
+	struct ubd *ubd_dev;
 	int err = -ENODEV;
 
-	spin_lock(&ubd_lock);
+	mutex_lock(&ubd_lock);
 
 	if(ubd_gendisk[n] == NULL)
 		goto out;
 
-	dev = &ubd_dev[n];
+	ubd_dev = &ubd_devs[n];
 
-	if(dev->file == NULL)
+	if(ubd_dev->file == NULL)
 		goto out;
 
 	/* you cannot remove a open disk */
 	err = -EBUSY;
-	if(dev->count > 0)
+	if(ubd_dev->count > 0)
 		goto out;
 
 	del_gendisk(ubd_gendisk[n]);
@@ -788,14 +807,15 @@ static int ubd_remove(int n)
 		fake_gendisk[n] = NULL;
 	}
 
-	platform_device_unregister(&dev->pdev);
-	*dev = ((struct ubd) DEFAULT_UBD);
+	platform_device_unregister(&ubd_dev->pdev);
+	*ubd_dev = ((struct ubd) DEFAULT_UBD);
 	err = 0;
 out:
-	spin_unlock(&ubd_lock);
+	mutex_unlock(&ubd_lock);
 	return err;
 }
 
+/* All these are called by mconsole in process context and without ubd-specific locks. */
 static struct mc_device ubd_mc = {
 	.name		= "ubd",
 	.config		= ubd_config,
@@ -804,7 +824,7 @@ static struct mc_device ubd_mc = {
 	.remove		= ubd_remove,
 };
 
-static int ubd_mc_init(void)
+static int __init ubd_mc_init(void)
 {
 	mconsole_register_dev(&ubd_mc);
 	return 0;
@@ -812,13 +832,24 @@ static int ubd_mc_init(void)
 
 __initcall(ubd_mc_init);
 
+static int __init ubd0_init(void)
+{
+	struct ubd *ubd_dev = &ubd_devs[0];
+
+	if(ubd_dev->file == NULL)
+		ubd_dev->file = "root_fs";
+	return(0);
+}
+
+__initcall(ubd0_init);
+
 static struct platform_driver ubd_driver = {
 	.driver = {
 		.name  = DRIVER_NAME,
 	},
 };
 
-int ubd_init(void)
+static int __init ubd_init(void)
 {
         int i;
 
@@ -846,7 +877,7 @@ int ubd_init(void)
 
 late_initcall(ubd_init);
 
-int ubd_driver_init(void){
+static int __init ubd_driver_init(void){
 	unsigned long stack;
 	int err;
 
@@ -867,7 +898,7 @@ int ubd_driver_init(void){
 		return(0);
 	}
 	err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr,
-			     IRQF_DISABLED, "ubd", ubd_dev);
+			     IRQF_DISABLED, "ubd", ubd_devs);
 	if(err != 0)
 		printk(KERN_ERR "um_request_irq failed - errno = %d\n", -err);
 	return 0;
@@ -878,24 +909,24 @@ device_initcall(ubd_driver_init);
 static int ubd_open(struct inode *inode, struct file *filp)
 {
 	struct gendisk *disk = inode->i_bdev->bd_disk;
-	struct ubd *dev = disk->private_data;
+	struct ubd *ubd_dev = disk->private_data;
 	int err = 0;
 
-	if(dev->count == 0){
-		err = ubd_open_dev(dev);
+	if(ubd_dev->count == 0){
+		err = ubd_open_dev(ubd_dev);
 		if(err){
 			printk(KERN_ERR "%s: Can't open \"%s\": errno = %d\n",
-			       disk->disk_name, dev->file, -err);
+			       disk->disk_name, ubd_dev->file, -err);
 			goto out;
 		}
 	}
-	dev->count++;
-	set_disk_ro(disk, !dev->openflags.w);
+	ubd_dev->count++;
+	set_disk_ro(disk, !ubd_dev->openflags.w);
 
 	/* This should no more be needed. And it didn't work anyway to exclude
 	 * read-write remounting of filesystems.*/
-	/*if((filp->f_mode & FMODE_WRITE) && !dev->openflags.w){
-	        if(--dev->count == 0) ubd_close(dev);
+	/*if((filp->f_mode & FMODE_WRITE) && !ubd_dev->openflags.w){
+	        if(--ubd_dev->count == 0) ubd_close_dev(ubd_dev);
 	        err = -EROFS;
 	}*/
  out:
@@ -905,10 +936,10 @@ static int ubd_open(struct inode *inode, struct file *filp)
 static int ubd_release(struct inode * inode, struct file * file)
 {
 	struct gendisk *disk = inode->i_bdev->bd_disk;
-	struct ubd *dev = disk->private_data;
+	struct ubd *ubd_dev = disk->private_data;
 
-	if(--dev->count == 0)
-		ubd_close(dev);
+	if(--ubd_dev->count == 0)
+		ubd_close_dev(ubd_dev);
 	return(0);
 }
 
@@ -976,12 +1007,12 @@ static void cowify_req(struct io_thread_req *req, unsigned long *bitmap,
 static int prepare_request(struct request *req, struct io_thread_req *io_req)
 {
 	struct gendisk *disk = req->rq_disk;
-	struct ubd *dev = disk->private_data;
+	struct ubd *ubd_dev = disk->private_data;
 	__u64 offset;
 	int len;
 
 	/* This should be impossible now */
-	if((rq_data_dir(req) == WRITE) && !dev->openflags.w){
+	if((rq_data_dir(req) == WRITE) && !ubd_dev->openflags.w){
 		printk("Write attempted on readonly ubd device %s\n",
 		       disk->disk_name);
 		end_request(req, 0);
@@ -991,8 +1022,8 @@ static int prepare_request(struct request *req, struct io_thread_req *io_req)
 	offset = ((__u64) req->sector) << 9;
 	len = req->current_nr_sectors << 9;
 
-	io_req->fds[0] = (dev->cow.file != NULL) ? dev->cow.fd : dev->fd;
-	io_req->fds[1] = dev->fd;
+	io_req->fds[0] = (ubd_dev->cow.file != NULL) ? ubd_dev->cow.fd : ubd_dev->fd;
+	io_req->fds[1] = ubd_dev->fd;
 	io_req->cow_offset = -1;
 	io_req->offset = offset;
 	io_req->length = len;
@@ -1001,13 +1032,13 @@ static int prepare_request(struct request *req, struct io_thread_req *io_req)
 
 	io_req->op = (rq_data_dir(req) == READ) ? UBD_READ : UBD_WRITE;
 	io_req->offsets[0] = 0;
-	io_req->offsets[1] = dev->cow.data_offset;
+	io_req->offsets[1] = ubd_dev->cow.data_offset;
 	io_req->buffer = req->buffer;
 	io_req->sectorsize = 1 << 9;
 
-	if(dev->cow.file != NULL)
-		cowify_req(io_req, dev->cow.bitmap, dev->cow.bitmap_offset,
-			   dev->cow.bitmap_len);
+	if(ubd_dev->cow.file != NULL)
+		cowify_req(io_req, ubd_dev->cow.bitmap, ubd_dev->cow.bitmap_offset,
+			   ubd_dev->cow.bitmap_len);
 
 	return(0);
 }
@@ -1033,7 +1064,7 @@ static void do_ubd_request(request_queue_t *q)
 			return;
 		err = prepare_request(req, &io_req);
 		if(!err){
-			do_ubd = ubd_handler;
+			do_ubd = 1;
 			n = os_write_file(thread_fd, (char *) &io_req,
 					 sizeof(io_req));
 			if(n != sizeof(io_req))
@@ -1045,18 +1076,18 @@ static void do_ubd_request(request_queue_t *q)
 
 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 {
-	struct ubd *dev = bdev->bd_disk->private_data;
+	struct ubd *ubd_dev = bdev->bd_disk->private_data;
 
 	geo->heads = 128;
 	geo->sectors = 32;
-	geo->cylinders = dev->size / (128 * 32 * 512);
+	geo->cylinders = ubd_dev->size / (128 * 32 * 512);
 	return 0;
 }
 
 static int ubd_ioctl(struct inode * inode, struct file * file,
 		     unsigned int cmd, unsigned long arg)
 {
-	struct ubd *dev = inode->i_bdev->bd_disk->private_data;
+	struct ubd *ubd_dev = inode->i_bdev->bd_disk->private_data;
 	struct hd_driveid ubd_id = {
 		.cyls		= 0,
 		.heads		= 128,
@@ -1066,7 +1097,7 @@ static int ubd_ioctl(struct inode * inode, struct file * file,
 	switch (cmd) {
 		struct cdrom_volctrl volume;
 	case HDIO_GET_IDENTITY:
-		ubd_id.cyls = dev->size / (128 * 32 * 512);
+		ubd_id.cyls = ubd_dev->size / (128 * 32 * 512);
 		if(copy_to_user((char __user *) arg, (char *) &ubd_id,
 				 sizeof(ubd_id)))
 			return(-EFAULT);
@@ -1353,8 +1384,8 @@ void do_io(struct io_thread_req *req)
  */
 int kernel_fd = -1;
 
-/* Only changed by the io thread */
-int io_count = 0;
+/* Only changed by the io thread. XXX: currently unused. */
+static int io_count = 0;
 
 int io_thread(void *arg)
 {
diff --git a/arch/um/include/mconsole.h b/arch/um/include/mconsole.h
index 58f67d39110..2666815b6af 100644
--- a/arch/um/include/mconsole.h
+++ b/arch/um/include/mconsole.h
@@ -61,6 +61,7 @@ struct mc_request
 
 	struct mconsole_request request;
 	struct mconsole_command *cmd;
+	union uml_pt_regs regs;
 };
 
 extern char mconsole_socket_name[];
diff --git a/arch/um/include/mconsole_kern.h b/arch/um/include/mconsole_kern.h
index d0b690197fd..1ea6d928e1c 100644
--- a/arch/um/include/mconsole_kern.h
+++ b/arch/um/include/mconsole_kern.h
@@ -14,6 +14,7 @@ struct mconsole_entry {
 	struct mc_request request;
 };
 
+/* All these methods are called in process context. */
 struct mc_device {
 	struct list_head list;
 	char *name;
diff --git a/arch/um/include/os.h b/arch/um/include/os.h
index 6516f6dca96..13a86bd383d 100644
--- a/arch/um/include/os.h
+++ b/arch/um/include/os.h
@@ -233,6 +233,8 @@ extern unsigned long __do_user_copy(void *to, const void *from, int n,
 				    void (*op)(void *to, const void *from,
 					       int n), int *faulted_out);
 
+/* execvp.c */
+extern int execvp_noalloc(char *buf, const char *file, char *const argv[]);
 /* helper.c */
 extern int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv,
 		      unsigned long *stack_out);
diff --git a/arch/um/include/sysdep-i386/barrier.h b/arch/um/include/sysdep-i386/barrier.h
new file mode 100644
index 00000000000..b58d52c5b2f
--- /dev/null
+++ b/arch/um/include/sysdep-i386/barrier.h
@@ -0,0 +1,9 @@
+#ifndef __SYSDEP_I386_BARRIER_H
+#define __SYSDEP_I386_BARRIER_H
+
+/* Copied from include/asm-i386 for use by userspace.  i386 has the option
+ * of using mfence, but I'm just using this, which works everywhere, for now.
+ */
+#define mb() asm volatile("lock; addl $0,0(%esp)")
+
+#endif
diff --git a/arch/um/include/sysdep-x86_64/barrier.h b/arch/um/include/sysdep-x86_64/barrier.h
new file mode 100644
index 00000000000..7b610befdc8
--- /dev/null
+++ b/arch/um/include/sysdep-x86_64/barrier.h
@@ -0,0 +1,7 @@
+#ifndef __SYSDEP_X86_64_BARRIER_H
+#define __SYSDEP_X86_64_BARRIER_H
+
+/* Copied from include/asm-x86_64 for use by userspace. */
+#define mb() 	asm volatile("mfence":::"memory")
+
+#endif
diff --git a/arch/um/kernel/dyn.lds.S b/arch/um/kernel/dyn.lds.S
index 68ed24df5c8..e36f92b463c 100644
--- a/arch/um/kernel/dyn.lds.S
+++ b/arch/um/kernel/dyn.lds.S
@@ -14,6 +14,7 @@ SECTIONS
    * is remapped.*/
   __binary_start = .;
   . = ALIGN(4096);		/* Init code and data */
+  _text = .;
   _stext = .;
   __init_begin = .;
   .init.text : {
diff --git a/arch/um/kernel/tt/tracer.c b/arch/um/kernel/tt/tracer.c
index 9882342206e..b9195355075 100644
--- a/arch/um/kernel/tt/tracer.c
+++ b/arch/um/kernel/tt/tracer.c
@@ -176,7 +176,6 @@ struct {
 int signal_index[32];
 int nsignals = 0;
 int debug_trace = 0;
-extern int io_nsignals, io_count, intr_count;
 
 extern void signal_usr1(int sig);
 
diff --git a/arch/um/kernel/uml.lds.S b/arch/um/kernel/uml.lds.S
index 8eca47a6ff0..f6301274cf3 100644
--- a/arch/um/kernel/uml.lds.S
+++ b/arch/um/kernel/uml.lds.S
@@ -25,6 +25,7 @@ SECTIONS
   . = ALIGN(4096);		/* Init code and data */
 #endif
 
+  _text = .;
   _stext = .;
   __init_begin = .;
   .init.text : {
diff --git a/arch/um/os-Linux/Makefile b/arch/um/os-Linux/Makefile
index b4183929b32..2f8c7946401 100644
--- a/arch/um/os-Linux/Makefile
+++ b/arch/um/os-Linux/Makefile
@@ -3,8 +3,8 @@
 # Licensed under the GPL
 #
 
-obj-y = aio.o elf_aux.o file.o helper.o irq.o main.o mem.o process.o sigio.o \
-	signal.o start_up.o time.o trap.o tty.o uaccess.o umid.o tls.o \
+obj-y = aio.o elf_aux.o execvp.o file.o helper.o irq.o main.o mem.o process.o \
+	sigio.o signal.o start_up.o time.o trap.o tty.o uaccess.o umid.o tls.o \
 	user_syms.o util.o drivers/ sys-$(SUBARCH)/
 
 obj-$(CONFIG_MODE_SKAS) += skas/
@@ -15,9 +15,9 @@ user-objs-$(CONFIG_MODE_TT) += tt.o
 obj-$(CONFIG_TTY_LOG) += tty_log.o
 user-objs-$(CONFIG_TTY_LOG) += tty_log.o
 
-USER_OBJS := $(user-objs-y) aio.o elf_aux.o file.o helper.o irq.o main.o mem.o \
-	process.o sigio.o signal.o start_up.o time.o trap.o tty.o tls.o \
-	uaccess.o umid.o util.o
+USER_OBJS := $(user-objs-y) aio.o elf_aux.o execvp.o file.o helper.o irq.o \
+	main.o mem.o process.o sigio.o signal.o start_up.o time.o trap.o tty.o \
+	tls.o uaccess.o umid.o util.o
 
 CFLAGS_user_syms.o += -DSUBARCH_$(SUBARCH)
 
diff --git a/arch/um/os-Linux/execvp.c b/arch/um/os-Linux/execvp.c
new file mode 100644
index 00000000000..66e583a4031
--- /dev/null
+++ b/arch/um/os-Linux/execvp.c
@@ -0,0 +1,149 @@
+/* Copyright (C) 2006 by Paolo Giarrusso - modified from glibc' execvp.c.
+   Original copyright notice follows:
+
+   Copyright (C) 1991,92,1995-99,2002,2004 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+#include <unistd.h>
+
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <limits.h>
+
+#ifndef TEST
+#include "um_malloc.h"
+#else
+#include <stdio.h>
+#define um_kmalloc malloc
+#endif
+#include "os.h"
+
+/* Execute FILE, searching in the `PATH' environment variable if it contains
+   no slashes, with arguments ARGV and environment from `environ'.  */
+int execvp_noalloc(char *buf, const char *file, char *const argv[])
+{
+	if (*file == '\0') {
+		return -ENOENT;
+	}
+
+	if (strchr (file, '/') != NULL) {
+		/* Don't search when it contains a slash.  */
+		execv(file, argv);
+	} else {
+		int got_eacces;
+		size_t len, pathlen;
+		char *name, *p;
+		char *path = getenv("PATH");
+		if (path == NULL)
+			path = ":/bin:/usr/bin";
+
+		len = strlen(file) + 1;
+		pathlen = strlen(path);
+		/* Copy the file name at the top.  */
+		name = memcpy(buf + pathlen + 1, file, len);
+		/* And add the slash.  */
+		*--name = '/';
+
+		got_eacces = 0;
+		p = path;
+		do {
+			char *startp;
+
+			path = p;
+			//Let's avoid this GNU extension.
+			//p = strchrnul (path, ':');
+			p = strchr(path, ':');
+			if (!p)
+				p = strchr(path, '\0');
+
+			if (p == path)
+				/* Two adjacent colons, or a colon at the beginning or the end
+				   of `PATH' means to search the current directory.  */
+				startp = name + 1;
+			else
+				startp = memcpy(name - (p - path), path, p - path);
+
+			/* Try to execute this name.  If it works, execv will not return.  */
+			execv(startp, argv);
+
+			/*
+			if (errno == ENOEXEC) {
+			}
+			*/
+
+			switch (errno) {
+				case EACCES:
+					/* Record the we got a `Permission denied' error.  If we end
+					   up finding no executable we can use, we want to diagnose
+					   that we did find one but were denied access.  */
+					got_eacces = 1;
+				case ENOENT:
+				case ESTALE:
+				case ENOTDIR:
+					/* Those errors indicate the file is missing or not executable
+					   by us, in which case we want to just try the next path
+					   directory.  */
+				case ENODEV:
+				case ETIMEDOUT:
+					/* Some strange filesystems like AFS return even
+					   stranger error numbers.  They cannot reasonably mean
+					   anything else so ignore those, too.  */
+				case ENOEXEC:
+					/* We won't go searching for the shell
+					 * if it is not executable - the Linux
+					 * kernel already handles this enough,
+					 * for us. */
+					break;
+
+				default:
+					/* Some other error means we found an executable file, but
+					   something went wrong executing it; return the error to our
+					   caller.  */
+					return -errno;
+			}
+		} while (*p++ != '\0');
+
+		/* We tried every element and none of them worked.  */
+		if (got_eacces)
+			/* At least one failure was due to permissions, so report that
+			   error.  */
+			return -EACCES;
+	}
+
+	/* Return the error from the last attempt (probably ENOENT).  */
+	return -errno;
+}
+#ifdef TEST
+int main(int argc, char**argv)
+{
+	char buf[PATH_MAX];
+	int ret;
+	argc--;
+	if (!argc) {
+		fprintf(stderr, "Not enough arguments\n");
+		return 1;
+	}
+	argv++;
+	if (ret = execvp_noalloc(buf, argv[0], argv)) {
+		errno = -ret;
+		perror("execvp_noalloc");
+	}
+	return 0;
+}
+#endif
diff --git a/arch/um/os-Linux/helper.c b/arch/um/os-Linux/helper.c
index d13299cfa31..c7ad6306e22 100644
--- a/arch/um/os-Linux/helper.c
+++ b/arch/um/os-Linux/helper.c
@@ -8,18 +8,21 @@
 #include <unistd.h>
 #include <errno.h>
 #include <sched.h>
+#include <limits.h>
 #include <sys/signal.h>
 #include <sys/wait.h>
 #include "user.h"
 #include "kern_util.h"
 #include "user_util.h"
 #include "os.h"
+#include "um_malloc.h"
 
 struct helper_data {
 	void (*pre_exec)(void*);
 	void *pre_data;
 	char **argv;
 	int fd;
+	char *buf;
 };
 
 /* Debugging aid, changed only from gdb */
@@ -41,9 +44,8 @@ static int helper_child(void *arg)
 	}
 	if (data->pre_exec != NULL)
 		(*data->pre_exec)(data->pre_data);
-	execvp(argv[0], argv);
-	errval = -errno;
-	printk("helper_child - execve of '%s' failed - errno = %d\n", argv[0], errno);
+	errval = execvp_noalloc(data->buf, argv[0], argv);
+	printk("helper_child - execvp of '%s' failed - errno = %d\n", argv[0], -errval);
 	os_write_file(data->fd, &errval, sizeof(errval));
 	kill(os_getpid(), SIGKILL);
 	return 0;
@@ -84,11 +86,13 @@ int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv,
 	data.pre_data = pre_data;
 	data.argv = argv;
 	data.fd = fds[1];
+	data.buf = __cant_sleep() ? um_kmalloc_atomic(PATH_MAX) :
+					um_kmalloc(PATH_MAX);
 	pid = clone(helper_child, (void *) sp, CLONE_VM | SIGCHLD, &data);
 	if (pid < 0) {
 		ret = -errno;
 		printk("run_helper : clone failed, errno = %d\n", errno);
-		goto out_close;
+		goto out_free2;
 	}
 
 	close(fds[1]);
@@ -109,6 +113,8 @@ int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv,
 		CATCH_EINTR(waitpid(pid, NULL, 0));
 	}
 
+out_free2:
+	kfree(data.buf);
 out_close:
 	if (fds[1] != -1)
 		close(fds[1]);
diff --git a/arch/um/os-Linux/process.c b/arch/um/os-Linux/process.c
index 51f0893640a..c692a192957 100644
--- a/arch/um/os-Linux/process.c
+++ b/arch/um/os-Linux/process.c
@@ -7,7 +7,6 @@
 #include <stdio.h>
 #include <errno.h>
 #include <signal.h>
-#include <linux/unistd.h>
 #include <sys/mman.h>
 #include <sys/wait.h>
 #include <sys/mman.h>
diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c
index 6b81739279d..b897e8592d7 100644
--- a/arch/um/os-Linux/signal.c
+++ b/arch/um/os-Linux/signal.c
@@ -15,6 +15,7 @@
 #include "user.h"
 #include "signal_kern.h"
 #include "sysdep/sigcontext.h"
+#include "sysdep/barrier.h"
 #include "sigcontext.h"
 #include "mode.h"
 #include "os.h"
@@ -34,8 +35,12 @@
 #define SIGALRM_BIT 2
 #define SIGALRM_MASK (1 << SIGALRM_BIT)
 
-static int signals_enabled = 1;
-static int pending = 0;
+/* These are used by both the signal handlers and
+ * block/unblock_signals.  I don't want modifications cached in a
+ * register - they must go straight to memory.
+ */
+static volatile int signals_enabled = 1;
+static volatile int pending = 0;
 
 void sig_handler(int sig, struct sigcontext *sc)
 {
@@ -152,6 +157,12 @@ int change_sig(int signal, int on)
 void block_signals(void)
 {
 	signals_enabled = 0;
+	/* This must return with signals disabled, so this barrier
+	 * ensures that writes are flushed out before the return.
+	 * This might matter if gcc figures out how to inline this and
+	 * decides to shuffle this code into the caller.
+	 */
+	mb();
 }
 
 void unblock_signals(void)
@@ -171,9 +182,23 @@ void unblock_signals(void)
 		 */
 		signals_enabled = 1;
 
+		/* Setting signals_enabled and reading pending must
+		 * happen in this order.
+		 */
+		mb();
+
 		save_pending = pending;
-		if(save_pending == 0)
+		if(save_pending == 0){
+			/* This must return with signals enabled, so
+			 * this barrier ensures that writes are
+			 * flushed out before the return.  This might
+			 * matter if gcc figures out how to inline
+			 * this (unlikely, given its size) and decides
+			 * to shuffle this code into the caller.
+			 */
+			mb();
 			return;
+		}
 
 		pending = 0;
 
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index cb9ab54146c..9b34fe65949 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -14,7 +14,7 @@
 #include <sys/mman.h>
 #include <sys/user.h>
 #include <sys/time.h>
-#include <asm/unistd.h>
+#include <sys/syscall.h>
 #include <asm/types.h>
 #include "user.h"
 #include "sysdep/ptrace.h"
diff --git a/arch/um/os-Linux/sys-i386/tls.c b/arch/um/os-Linux/sys-i386/tls.c
index 6e945ab4584..256532034c6 100644
--- a/arch/um/os-Linux/sys-i386/tls.c
+++ b/arch/um/os-Linux/sys-i386/tls.c
@@ -1,6 +1,9 @@
 #include <errno.h>
 #include <linux/unistd.h>
+
 #include <sys/syscall.h>
+#include <unistd.h>
+
 #include "sysdep/tls.h"
 #include "user_util.h"
 
diff --git a/arch/um/os-Linux/tls.c b/arch/um/os-Linux/tls.c
index a2de2580b8a..16215b99080 100644
--- a/arch/um/os-Linux/tls.c
+++ b/arch/um/os-Linux/tls.c
@@ -1,4 +1,5 @@
 #include <errno.h>
+#include <unistd.h>
 #include <sys/ptrace.h>
 #include <sys/syscall.h>
 #include <asm/ldt.h>
diff --git a/arch/um/sys-i386/unmap.c b/arch/um/sys-i386/unmap.c
index 8e55cd5d3d0..1b0ad0e4adc 100644
--- a/arch/um/sys-i386/unmap.c
+++ b/arch/um/sys-i386/unmap.c
@@ -5,17 +5,20 @@
 
 #include <linux/mman.h>
 #include <asm/unistd.h>
-#include <sys/syscall.h>
 
+static int errno;
+
+static inline _syscall2(int,munmap,void *,start,size_t,len)
+static inline _syscall6(void *,mmap2,void *,addr,size_t,len,int,prot,int,flags,int,fd,off_t,offset)
 int switcheroo(int fd, int prot, void *from, void *to, int size)
 {
-	if (syscall(__NR_munmap, to, size) < 0){
+	if(munmap(to, size) < 0){
 		return(-1);
 	}
-	if (syscall(__NR_mmap2, to, size, prot, MAP_SHARED | MAP_FIXED, fd, 0) == (void*) -1 ){
+	if(mmap2(to, size, prot, MAP_SHARED | MAP_FIXED, fd, 0) == (void*) -1 ){
 		return(-1);
 	}
-	if (syscall(__NR_munmap, from, size) < 0){
+	if(munmap(from, size) < 0){
 		return(-1);
 	}
 	return(0);
diff --git a/arch/um/sys-x86_64/unmap.c b/arch/um/sys-x86_64/unmap.c
index 57c9286a701..f4a4bffd8a1 100644
--- a/arch/um/sys-x86_64/unmap.c
+++ b/arch/um/sys-x86_64/unmap.c
@@ -5,17 +5,20 @@
 
 #include <linux/mman.h>
 #include <asm/unistd.h>
-#include <sys/syscall.h>
 
+static int errno;
+
+static inline _syscall2(int,munmap,void *,start,size_t,len)
+static inline _syscall6(void *,mmap,void *,addr,size_t,len,int,prot,int,flags,int,fd,off_t,offset)
 int switcheroo(int fd, int prot, void *from, void *to, int size)
 {
-	if (syscall(__NR_munmap, to, size) < 0){
+	if(munmap(to, size) < 0){
 		return(-1);
 	}
-	if (syscall(__NR_mmap, to, size, prot, MAP_SHARED | MAP_FIXED, fd, 0) == (void*) -1){
+	if(mmap(to, size, prot, MAP_SHARED | MAP_FIXED, fd, 0) == (void*) -1){
 		return(-1);
 	}
-	if (syscall(__NR_munmap, from, size) < 0){
+	if(munmap(from, size) < 0){
 		return(-1);
 	}
 	return(0);