From f71ad62a264a89cb1952df0c92b167005de8d1b0 Mon Sep 17 00:00:00 2001 From: Michael Holzheu Date: Fri, 30 May 2008 10:03:25 +0200 Subject: [S390] tape: Fix race condition in tape block device driver Due to incorrect function call sequence it can happen that a tape block request is finished before the request is taken from the block request queue. The following sequence leads to that condition: * tapeblock_start_request() -> start CCW program * Request finishes -> IO interrupt * tapeblock_end_request() * end_that_request_last() If blkdev_dequeue_request() has not been called before end_that_request_last(), a kernel bug is triggered in end_that_request_last() because the request is still queued. To solve that problem blkdev_dequeue_request() has to be called before starting the CCW program. Signed-off-by: Michael Holzheu Signed-off-by: Martin Schwidefsky --- drivers/s390/char/tape_block.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers') diff --git a/drivers/s390/char/tape_block.c b/drivers/s390/char/tape_block.c index ddc4a114e7f..95da72bc17e 100644 --- a/drivers/s390/char/tape_block.c +++ b/drivers/s390/char/tape_block.c @@ -179,11 +179,11 @@ tapeblock_requeue(struct work_struct *work) { tapeblock_end_request(req, -EIO); continue; } + blkdev_dequeue_request(req); + nr_queued++; spin_unlock_irq(&device->blk_data.request_queue_lock); rc = tapeblock_start_request(device, req); spin_lock_irq(&device->blk_data.request_queue_lock); - blkdev_dequeue_request(req); - nr_queued++; } spin_unlock_irq(&device->blk_data.request_queue_lock); atomic_set(&device->blk_data.requeue_scheduled, 0); -- cgit v1.2.3 From 67060d9c1f5d91c917cc51bed464cb5638eaddbc Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Fri, 30 May 2008 10:03:27 +0200 Subject: [S390] Fix section mismatch warnings. This fixes the last remaining section mismatch warnings in s390 architecture code. It reveals also a real bug introduced by... me with git commit 2069e978d5a6e7b45d58027e3de7f879b8c5e488 ("[S390] sparsemem vmemmap: initialize memmap.") Calling the generic vmemmap_alloc_block() function to get initialized memory is a nice idea, however that function is __meminit annotated and therefore the function might be gone if we try to call it later. This can happen if a DCSS segment gets added. So basically revert the patch and clear the memmap explicitly to fix the original bug. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- drivers/s390/char/sclp_config.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers') diff --git a/drivers/s390/char/sclp_config.c b/drivers/s390/char/sclp_config.c index 9e784d5f7f5..ad05a87bc48 100644 --- a/drivers/s390/char/sclp_config.c +++ b/drivers/s390/char/sclp_config.c @@ -40,7 +40,7 @@ static void sclp_cpu_capability_notify(struct work_struct *work) put_online_cpus(); } -static void sclp_cpu_change_notify(struct work_struct *work) +static void __ref sclp_cpu_change_notify(struct work_struct *work) { smp_rescan_cpus(); } -- cgit v1.2.3 From d4820e44b0ae6830b1d634e6d0a425d839388c06 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Fri, 30 May 2008 10:03:30 +0200 Subject: [S390] sclp_vt220: fix scheduling while atomic bug. The driver incorrectly assumed that putchar will only be called from schedulable process context and therefore blocked and waited if no free output buffers where available. Since putchar may also be called from BH context this may lead to deadlocks. To fix this just return the number of characters accepted and let the upper layer handle the rest. The console write function will busy wait (sclp_sync_wait) until a buffer is available again. Cc: Peter Oberparleiter Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- drivers/s390/char/sclp_vt220.c | 27 +++++++-------------------- 1 file changed, 7 insertions(+), 20 deletions(-) (limited to 'drivers') diff --git a/drivers/s390/char/sclp_vt220.c b/drivers/s390/char/sclp_vt220.c index 35707c04e61..62576af36f4 100644 --- a/drivers/s390/char/sclp_vt220.c +++ b/drivers/s390/char/sclp_vt220.c @@ -71,9 +71,6 @@ static struct list_head sclp_vt220_outqueue; /* Number of requests in outqueue */ static int sclp_vt220_outqueue_count; -/* Wait queue used to delay write requests while we've run out of buffers */ -static wait_queue_head_t sclp_vt220_waitq; - /* Timer used for delaying write requests to merge subsequent messages into * a single buffer */ static struct timer_list sclp_vt220_timer; @@ -133,7 +130,6 @@ sclp_vt220_process_queue(struct sclp_vt220_request *request) } while (request && __sclp_vt220_emit(request)); if (request == NULL && sclp_vt220_flush_later) sclp_vt220_emit_current(); - wake_up(&sclp_vt220_waitq); /* Check if the tty needs a wake up call */ if (sclp_vt220_tty != NULL) { tty_wakeup(sclp_vt220_tty); @@ -383,7 +379,7 @@ sclp_vt220_timeout(unsigned long data) */ static int __sclp_vt220_write(const unsigned char *buf, int count, int do_schedule, - int convertlf, int may_schedule) + int convertlf, int may_fail) { unsigned long flags; void *page; @@ -395,15 +391,14 @@ __sclp_vt220_write(const unsigned char *buf, int count, int do_schedule, overall_written = 0; spin_lock_irqsave(&sclp_vt220_lock, flags); do { - /* Create a sclp output buffer if none exists yet */ + /* Create an sclp output buffer if none exists yet */ if (sclp_vt220_current_request == NULL) { while (list_empty(&sclp_vt220_empty)) { spin_unlock_irqrestore(&sclp_vt220_lock, flags); - if (in_interrupt() || !may_schedule) - sclp_sync_wait(); + if (may_fail) + goto out; else - wait_event(sclp_vt220_waitq, - !list_empty(&sclp_vt220_empty)); + sclp_sync_wait(); spin_lock_irqsave(&sclp_vt220_lock, flags); } page = (void *) sclp_vt220_empty.next; @@ -437,6 +432,7 @@ __sclp_vt220_write(const unsigned char *buf, int count, int do_schedule, add_timer(&sclp_vt220_timer); } spin_unlock_irqrestore(&sclp_vt220_lock, flags); +out: return overall_written; } @@ -520,19 +516,11 @@ sclp_vt220_close(struct tty_struct *tty, struct file *filp) * character to the tty device. If the kernel uses this routine, * it must call the flush_chars() routine (if defined) when it is * done stuffing characters into the driver. - * - * NOTE: include/linux/tty_driver.h specifies that a character should be - * ignored if there is no room in the queue. This driver implements a different - * semantic in that it will block when there is no more room left. - * - * FIXME: putchar can currently be called from BH and other non blocking - * handlers so this semantic isn't a good idea. */ static int sclp_vt220_put_char(struct tty_struct *tty, unsigned char ch) { - __sclp_vt220_write(&ch, 1, 0, 0, 1); - return 1; + return __sclp_vt220_write(&ch, 1, 0, 0, 1); } /* @@ -653,7 +641,6 @@ static int __init __sclp_vt220_init(void) spin_lock_init(&sclp_vt220_lock); INIT_LIST_HEAD(&sclp_vt220_empty); INIT_LIST_HEAD(&sclp_vt220_outqueue); - init_waitqueue_head(&sclp_vt220_waitq); init_timer(&sclp_vt220_timer); sclp_vt220_current_request = NULL; sclp_vt220_buffered_chars = 0; -- cgit v1.2.3 From c80ee724966a8ce9a68020d9095233fb1c6f57e8 Mon Sep 17 00:00:00 2001 From: Stefan Haberland Date: Fri, 30 May 2008 10:03:31 +0200 Subject: [S390] dasd: use a generic wait_queue for sleep_on Use a generic wait_queue to prevent the wait_queue in dasd_sleep_on_ functions from being referenced by callback_data while it does not exist any more. Signed-off-by: Stefan Haberland Signed-off-by: Martin Schwidefsky --- drivers/s390/block/dasd.c | 28 ++++++++++++++-------------- 1 file changed, 14 insertions(+), 14 deletions(-) (limited to 'drivers') diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c index 8ba3f135da2..1a402568336 100644 --- a/drivers/s390/block/dasd.c +++ b/drivers/s390/block/dasd.c @@ -63,6 +63,7 @@ static void dasd_return_cqr_cb(struct dasd_ccw_req *, void *); */ static wait_queue_head_t dasd_init_waitq; static wait_queue_head_t dasd_flush_wq; +static wait_queue_head_t generic_waitq; /* * Allocate memory for a new device structure. @@ -1151,11 +1152,15 @@ static void __dasd_device_process_final_queue(struct dasd_device *device, struct list_head *l, *n; struct dasd_ccw_req *cqr; struct dasd_block *block; + void (*callback)(struct dasd_ccw_req *, void *data); + void *callback_data; list_for_each_safe(l, n, final_queue) { cqr = list_entry(l, struct dasd_ccw_req, devlist); list_del_init(&cqr->devlist); block = cqr->block; + callback = cqr->callback; + callback_data = cqr->callback_data; if (block) spin_lock_bh(&block->queue_lock); switch (cqr->status) { @@ -1176,7 +1181,7 @@ static void __dasd_device_process_final_queue(struct dasd_device *device, BUG(); } if (cqr->callback != NULL) - (cqr->callback)(cqr, cqr->callback_data); + (callback)(cqr, callback_data); if (block) spin_unlock_bh(&block->queue_lock); } @@ -1406,17 +1411,15 @@ static inline int _wait_for_wakeup(struct dasd_ccw_req *cqr) */ int dasd_sleep_on(struct dasd_ccw_req *cqr) { - wait_queue_head_t wait_q; struct dasd_device *device; int rc; device = cqr->startdev; - init_waitqueue_head (&wait_q); cqr->callback = dasd_wakeup_cb; - cqr->callback_data = (void *) &wait_q; + cqr->callback_data = (void *) &generic_waitq; dasd_add_request_tail(cqr); - wait_event(wait_q, _wait_for_wakeup(cqr)); + wait_event(generic_waitq, _wait_for_wakeup(cqr)); /* Request status is either done or failed. */ rc = (cqr->status == DASD_CQR_DONE) ? 0 : -EIO; @@ -1429,20 +1432,18 @@ int dasd_sleep_on(struct dasd_ccw_req *cqr) */ int dasd_sleep_on_interruptible(struct dasd_ccw_req *cqr) { - wait_queue_head_t wait_q; struct dasd_device *device; int rc; device = cqr->startdev; - init_waitqueue_head (&wait_q); cqr->callback = dasd_wakeup_cb; - cqr->callback_data = (void *) &wait_q; + cqr->callback_data = (void *) &generic_waitq; dasd_add_request_tail(cqr); - rc = wait_event_interruptible(wait_q, _wait_for_wakeup(cqr)); + rc = wait_event_interruptible(generic_waitq, _wait_for_wakeup(cqr)); if (rc == -ERESTARTSYS) { dasd_cancel_req(cqr); /* wait (non-interruptible) for final status */ - wait_event(wait_q, _wait_for_wakeup(cqr)); + wait_event(generic_waitq, _wait_for_wakeup(cqr)); } rc = (cqr->status == DASD_CQR_DONE) ? 0 : -EIO; return rc; @@ -1466,7 +1467,6 @@ static inline int _dasd_term_running_cqr(struct dasd_device *device) int dasd_sleep_on_immediatly(struct dasd_ccw_req *cqr) { - wait_queue_head_t wait_q; struct dasd_device *device; int rc; @@ -1478,9 +1478,8 @@ int dasd_sleep_on_immediatly(struct dasd_ccw_req *cqr) return rc; } - init_waitqueue_head (&wait_q); cqr->callback = dasd_wakeup_cb; - cqr->callback_data = (void *) &wait_q; + cqr->callback_data = (void *) &generic_waitq; cqr->status = DASD_CQR_QUEUED; list_add(&cqr->devlist, &device->ccw_queue); @@ -1489,7 +1488,7 @@ int dasd_sleep_on_immediatly(struct dasd_ccw_req *cqr) spin_unlock_irq(get_ccwdev_lock(device->cdev)); - wait_event(wait_q, _wait_for_wakeup(cqr)); + wait_event(generic_waitq, _wait_for_wakeup(cqr)); /* Request status is either done or failed. */ rc = (cqr->status == DASD_CQR_DONE) ? 0 : -EIO; @@ -2430,6 +2429,7 @@ static int __init dasd_init(void) init_waitqueue_head(&dasd_init_waitq); init_waitqueue_head(&dasd_flush_wq); + init_waitqueue_head(&generic_waitq); /* register 'common' DASD debug area, used for all DBF_XXX calls */ dasd_debug_area = debug_register("dasd", 1, 1, 8 * sizeof(long)); -- cgit v1.2.3 From 54ad64129cc166b9eec7151f3f9fc83589e33555 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Fri, 30 May 2008 10:03:32 +0200 Subject: [S390] 3270: fix race with stack local wait_queue_head_t. A wait_event call with a stack local wait_queue_head_t structure that is used to do the wake up for the wait_event is inherently racy. After the wait_event finished the wake_up call might not have completed yet. Remove the stack local wait_queue_head_t from raw3270_start_init and use the global raw3270_wait_queue instead. Signed-off-by: Martin Schwidefsky --- drivers/s390/char/raw3270.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) (limited to 'drivers') diff --git a/drivers/s390/char/raw3270.c b/drivers/s390/char/raw3270.c index 0d98f1ff2ed..848ef7e8523 100644 --- a/drivers/s390/char/raw3270.c +++ b/drivers/s390/char/raw3270.c @@ -549,7 +549,6 @@ raw3270_start_init(struct raw3270 *rp, struct raw3270_view *view, struct raw3270_request *rq) { unsigned long flags; - wait_queue_head_t wq; int rc; #ifdef CONFIG_TN3270_CONSOLE @@ -566,20 +565,20 @@ raw3270_start_init(struct raw3270 *rp, struct raw3270_view *view, return rq->rc; } #endif - init_waitqueue_head(&wq); rq->callback = raw3270_wake_init; - rq->callback_data = &wq; + rq->callback_data = &raw3270_wait_queue; spin_lock_irqsave(get_ccwdev_lock(view->dev->cdev), flags); rc = __raw3270_start(rp, view, rq); spin_unlock_irqrestore(get_ccwdev_lock(view->dev->cdev), flags); if (rc) return rc; /* Now wait for the completion. */ - rc = wait_event_interruptible(wq, raw3270_request_final(rq)); + rc = wait_event_interruptible(raw3270_wait_queue, + raw3270_request_final(rq)); if (rc == -ERESTARTSYS) { /* Interrupted by a signal. */ raw3270_halt_io(view->dev, rq); /* No wait for the halt to complete. */ - wait_event(wq, raw3270_request_final(rq)); + wait_event(raw3270_wait_queue, raw3270_request_final(rq)); return -ERESTARTSYS; } return rq->rc; -- cgit v1.2.3 From 4657fb8a98a4e02981a574492bbe470c147b6657 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Fri, 30 May 2008 10:03:33 +0200 Subject: [S390] tape: fix race with stack local wait_queue_head_t. A wait_event call with a stack local wait_queue_head_t structure that is used to do the wake up for the wait_event is inherently racy. After the wait_event finished the wake_up call might not have completed yet. Replace the stack local wait_queue_head_t in tape_do_io and tape_do_io_interruptible with a per device wait queue. Signed-off-by: Martin Schwidefsky --- drivers/s390/char/tape.h | 3 +++ drivers/s390/char/tape_core.c | 16 +++++++--------- 2 files changed, 10 insertions(+), 9 deletions(-) (limited to 'drivers') diff --git a/drivers/s390/char/tape.h b/drivers/s390/char/tape.h index dddf8d62c15..d0d565a05df 100644 --- a/drivers/s390/char/tape.h +++ b/drivers/s390/char/tape.h @@ -231,6 +231,9 @@ struct tape_device { /* Request queue. */ struct list_head req_queue; + /* Request wait queue. */ + wait_queue_head_t wait_queue; + /* Each tape device has (currently) two minor numbers. */ int first_minor; diff --git a/drivers/s390/char/tape_core.c b/drivers/s390/char/tape_core.c index 76e44eb7c47..c20e3c54834 100644 --- a/drivers/s390/char/tape_core.c +++ b/drivers/s390/char/tape_core.c @@ -449,6 +449,7 @@ tape_alloc_device(void) INIT_LIST_HEAD(&device->req_queue); INIT_LIST_HEAD(&device->node); init_waitqueue_head(&device->state_change_wq); + init_waitqueue_head(&device->wait_queue); device->tape_state = TS_INIT; device->medium_state = MS_UNKNOWN; *device->modeset_byte = 0; @@ -954,21 +955,19 @@ __tape_wake_up(struct tape_request *request, void *data) int tape_do_io(struct tape_device *device, struct tape_request *request) { - wait_queue_head_t wq; int rc; - init_waitqueue_head(&wq); spin_lock_irq(get_ccwdev_lock(device->cdev)); /* Setup callback */ request->callback = __tape_wake_up; - request->callback_data = &wq; + request->callback_data = &device->wait_queue; /* Add request to request queue and try to start it. */ rc = __tape_start_request(device, request); spin_unlock_irq(get_ccwdev_lock(device->cdev)); if (rc) return rc; /* Request added to the queue. Wait for its completion. */ - wait_event(wq, (request->callback == NULL)); + wait_event(device->wait_queue, (request->callback == NULL)); /* Get rc from request */ return request->rc; } @@ -989,20 +988,19 @@ int tape_do_io_interruptible(struct tape_device *device, struct tape_request *request) { - wait_queue_head_t wq; int rc; - init_waitqueue_head(&wq); spin_lock_irq(get_ccwdev_lock(device->cdev)); /* Setup callback */ request->callback = __tape_wake_up_interruptible; - request->callback_data = &wq; + request->callback_data = &device->wait_queue; rc = __tape_start_request(device, request); spin_unlock_irq(get_ccwdev_lock(device->cdev)); if (rc) return rc; /* Request added to the queue. Wait for its completion. */ - rc = wait_event_interruptible(wq, (request->callback == NULL)); + rc = wait_event_interruptible(device->wait_queue, + (request->callback == NULL)); if (rc != -ERESTARTSYS) /* Request finished normally. */ return request->rc; @@ -1015,7 +1013,7 @@ tape_do_io_interruptible(struct tape_device *device, /* Wait for the interrupt that acknowledges the halt. */ do { rc = wait_event_interruptible( - wq, + device->wait_queue, (request->callback == NULL) ); } while (rc == -ERESTARTSYS); -- cgit v1.2.3