From b4fd310e163477236a241580b3b8c29aee65f4cc Mon Sep 17 00:00:00 2001 From: Jeff Dike Date: Fri, 16 Sep 2005 19:27:49 -0700 Subject: [PATCH] uml: preserve errno in error paths The poster child for this patch is the third tuntap_user hunk. When an ioctl fails, it properly closes the opened file descriptor and returns. However, the close resets errno to 0, and the 'return errno' that follows returns 0 rather than the value that ioctl set. This caused the caller to believe that the device open succeeded and had opened file descriptor 0, which caused no end of interesting behavior. The rest of this patch is a pass through the UML sources looking for places where errno could be reset before being passed back out. A common culprit is printk, which could call write, being called before errno is returned. In some cases, where the code ends up being much smaller, I just deleted the printk. There was another case where a caller of run_helper looked at errno after a failure, rather than the return value of run_helper, which was the errno value that it wanted. Signed-off-by: Jeff Dike Cc: Paolo Giarrusso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/kernel/helper.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) (limited to 'arch/um/kernel/helper.c') diff --git a/arch/um/kernel/helper.c b/arch/um/kernel/helper.c index f83e1e8e239..33fb0bd3b11 100644 --- a/arch/um/kernel/helper.c +++ b/arch/um/kernel/helper.c @@ -85,8 +85,8 @@ int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv, data.fd = fds[1]; pid = clone(helper_child, (void *) sp, CLONE_VM | SIGCHLD, &data); if(pid < 0){ - printk("run_helper : clone failed, errno = %d\n", errno); ret = -errno; + printk("run_helper : clone failed, errno = %d\n", errno); goto out_close; } @@ -122,7 +122,7 @@ int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags, unsigned long *stack_out, int stack_order) { unsigned long stack, sp; - int pid, status; + int pid, status, err; stack = alloc_stack(stack_order, um_in_interrupt()); if(stack == 0) return(-ENOMEM); @@ -130,16 +130,18 @@ int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags, sp = stack + (page_size() << stack_order) - sizeof(void *); pid = clone(proc, (void *) sp, flags | SIGCHLD, arg); if(pid < 0){ + err = -errno; printk("run_helper_thread : clone failed, errno = %d\n", errno); - return(-errno); + return err; } if(stack_out == NULL){ CATCH_EINTR(pid = waitpid(pid, &status, 0)); if(pid < 0){ + err = -errno; printk("run_helper_thread - wait failed, errno = %d\n", errno); - pid = -errno; + pid = err; } if(!WIFEXITED(status) || (WEXITSTATUS(status) != 0)) printk("run_helper_thread - thread returned status " @@ -156,8 +158,8 @@ int helper_wait(int pid) CATCH_EINTR(ret = waitpid(pid, NULL, WNOHANG)); if(ret < 0){ + ret = -errno; printk("helper_wait : waitpid failed, errno = %d\n", errno); - return(-errno); } return(ret); } -- cgit v1.2.3