user/sven/linux.git/include/linux/wait.h, branch v3.4.92

SCSI: zfcp: fix lock imbalance by reworking request queue locking

2013-08-29T16:50:13Z

commit d79ff142624e1be080ad8d09101f7004d79c36e1 upstream. This patch adds wait_event_interruptible_lock_irq_timeout(), which is a straight-forward descendant of wait_event_interruptible_timeout() and wait_event_interruptible_lock_irq(). The zfcp driver used to call wait_event_interruptible_timeout() in combination with some intricate and error-prone locking. Using wait_event_interruptible_lock_irq_timeout() as a replacement nicely cleans up that locking. This rework removes a situation that resulted in a locking imbalance in zfcp_qdio_sbal_get(): BUG: workqueue leaked lock or atomic: events/1/0xffffff00/10 last function: zfcp_fc_wka_port_offline+0x0/0xa0 [zfcp] It was introduced by commit c2af7545aaff3495d9bf9a7608c52f0af86fb194 "[SCSI] zfcp: Do not wait for SBALs on stopped queue", which had a new code path related to ZFCP_STATUS_ADAPTER_QDIOUP that took an early exit without a required lock being held. The problem occured when a special, non-SCSI I/O request was being submitted in process context, when the adapter's queues had been torn down. In this case the bug surfaced when the Fibre Channel port connection for a well-known address was closed during a concurrent adapter shut-down procedure, which is a rare constellation. This patch also fixes these warnings from the sparse tool (make C=1): drivers/s390/scsi/zfcp_qdio.c:224:12: warning: context imbalance in 'zfcp_qdio_sbal_check' - wrong count at exit drivers/s390/scsi/zfcp_qdio.c:244:5: warning: context imbalance in 'zfcp_qdio_sbal_get' - unexpected unlock Last but not least, we get rid of that crappy lock-unlock-lock sequence at the beginning of the critical section. It is okay to call zfcp_erp_adapter_reopen() with req_q_lock held. Reported-by: Mikulas Patocka Reported-by: Heiko Carstens Signed-off-by: Martin Peschke Signed-off-by: Steffen Maier Signed-off-by: James Bottomley Signed-off-by: Greg Kroah-Hartman

wait: fix false timeouts when using wait_event_timeout()

2013-06-07T19:49:14Z

commit 4c663cfc523a88d97a8309b04a089c27dc57fd7e upstream. Many callers of the wait_event_timeout() and wait_event_interruptible_timeout() expect that the return value will be positive if the specified condition becomes true before the timeout elapses. However, at the moment this isn't guaranteed. If the wake-up handler is delayed enough, the time remaining until timeout will be calculated as 0 - and passed back as a return value - even if the condition became true before the timeout has passed. Fix this by returning at least 1 if the condition becomes true. This semantic is in line with what wait_for_condition_timeout() does; see commit bb10ed09 ("sched: fix wait_for_completion_timeout() spurious failure under heavy load"). Daniel said "We have 3 instances of this bug in drm/i915. One case even where we switch between the interruptible and not interruptible wait_event_timeout variants, foolishly presuming they have the same semantics. I very much like this." One such bug is reported at https://bugs.freedesktop.org/show_bug.cgi?id=64133 Signed-off-by: Imre Deak Acked-by: Daniel Vetter Acked-by: David Howells Acked-by: Jens Axboe Cc: "Paul E. McKenney" Cc: Dave Jones Cc: Lukas Czerner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

Remove all #inclusions of asm/system.h

2012-03-28T17:30:03Z

Remove all #inclusions of asm/system.h preparatory to splitting and killing it. Performed with the following command: perl -p -i -e 's!^#\s*include\s*.*\n!!' `grep -Irl '^#\s*include\s*' *` Signed-off-by: David Howells

sched/wait: Add __wake_up_all_locked() API

2012-03-01T09:28:04Z

For code which protects the waitqueue itself with another lock it makes no sense to acquire the waitqueue lock for wakeup all. Provide __wake_up_all_locked(). This is an optimization on the vanilla kernel (to be used by the PCI code) and an important semantic distinction on -rt. Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra Link: http://lkml.kernel.org/n/tip-ux6m4b8jonb9inx8xafh77ds@git.kernel.org Signed-off-by: Ingo Molnar

lockdep/waitqueues: Add better annotation

2011-12-21T09:07:39Z

-> #2 (&tty->write_wait){-.-...}: is a lot more informative than: -> #2 (key#19){-.....}: Signed-off-by: Peter Zijlstra Cc: Andrew Morton Cc: Linus Torvalds Link: http://lkml.kernel.org/n/tip-8zpopbny51023rdb0qq67eye@git.kernel.org Signed-off-by: Ingo Molnar

wait: using uninitialized member of wait queue

2010-10-05T18:47:18Z

The "flags" member of "struct wait_queue_t" is used in several places in the kernel code without beeing initialized by init_wait(). "flags" is used in bitwise operations. If "flags" not initialized then unexpected behaviour may take place. Incorrect flags might used later in code. Added initialization of "wait_queue_t.flags" with zero value into "init_wait". Signed-off-by: Evgeny Kuznetsov [ The bit we care about does end up being initialized by both prepare_to_wait() and add_to_wait_queue(), so this doesn't seem to cause actual bugs, but is definitely the right thing to do -Linus ] Signed-off-by: Linus Torvalds

Merge git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6

2010-05-21T04:26:12Z

* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6: (229 commits) USB: remove unused usb_buffer_alloc and usb_buffer_free macros usb: musb: update gfp/slab.h includes USB: ftdi_sio: fix legacy SIO-device header USB: kl5usb105: reimplement using generic framework USB: kl5usb105: minor clean ups USB: kl5usb105: fix memory leak USB: io_ti: use kfifo to implement write buffering USB: io_ti: remove unsused private counter USB: ti_usb: use kfifo to implement write buffering USB: ir-usb: fix incorrect write-buffer length USB: aircable: fix incorrect write-buffer length USB: safe_serial: straighten out read processing USB: safe_serial: reimplement read using generic framework USB: safe_serial: reimplement write using generic framework usb-storage: always print quirks USB: usb-storage: trivial debug improvements USB: oti6858: use port write fifo USB: oti6858: use kfifo to implement write buffering USB: cypress_m8: use kfifo to implement write buffering USB: cypress_m8: remove unused drain define ... Fix up conflicts (due to usb_buffer_alloc/free renaming) in drivers/input/tablet/acecad.c drivers/input/tablet/kbtab.c drivers/input/tablet/wacom_sys.c drivers/media/video/gspca/gspca.c sound/usb/usbaudio.c

wait_event_interruptible_locked() interface

2010-05-20T20:21:42Z

New wait_event_interruptible{,_exclusive}_locked{,_irq} macros added. They work just like versions without _locked* suffix but require the wait queue's lock to be held. Also __wake_up_locked() is now exported as to pair it with the above macros. The use case of this new facility is when one uses wait queue's lock to protect a data structure. This may be advantageous if the structure needs to be protected by a spinlock anyway. In particular, with additional spinlock the following code has to be used to wait for a condition: spin_lock(&data.lock); ... for (ret = 0; !ret && !(condition); ) { spin_unlock(&data.lock); ret = wait_event_interruptible(data.wqh, (condition)); spin_lock(&data.lock); } ... spin_unlock(&data.lock); This looks bizarre plus wait_event_interruptible() locks the wait queue's lock anyway so there is a unlock+lock sequence where it could be avoided. To avoid those problems and benefit from wait queue's lock, a code similar to the following should be used: /* Waiting */ spin_lock(&data.wqh.lock); ... ret = wait_event_interruptible_locked(data.wqh, (condition)); ... spin_unlock(&data.wqh.lock); /* Waiting exclusively */ spin_lock(&data.whq.lock); ... ret = wait_event_interruptible_exclusive_locked(data.whq, (condition)); ... spin_unlock(&data.whq.lock); /* Waking up */ spin_lock(&data.wqh.lock); ... wake_up_locked(&data.wqh); ... spin_unlock(&data.wqh.lock); When spin_lock_irq() is used matching versions of macros need to be used (*_locked_irq()). Signed-off-by: Michal Nazarewicz Cc: Kyungmin Park Cc: Marek Szyprowski Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Takashi Iwai Cc: David Howells Cc: Andreas Herrmann Cc: Thomas Gleixner Cc: Mike Galbraith Signed-off-by: Greg Kroah-Hartman

sched, wait: Use wrapper functions

2010-05-11T15:43:58Z

epoll should not touch flags in wait_queue_t. This patch introduces a new function __add_wait_queue_exclusive(), for the users, who use wait queue as a LIFO queue. __add_wait_queue_tail_exclusive() is introduced too instead of add_wait_queue_exclusive_locked(). remove_wait_queue_locked() is removed, as it is a duplicate of __remove_wait_queue(), disliked by users, and with less users. Signed-off-by: Changli Gao Signed-off-by: Peter Zijlstra Cc: Alexander Viro Cc: Paul Menage Cc: Li Zefan Cc: Davide Libenzi Cc: LKML-Reference: <1273214006-2979-1-git-send-email-xiaosuo@gmail.com> Signed-off-by: Ingo Molnar

sched: Rename sync arguments

2009-09-15T14:51:30Z

In order to extend the functions to have more than 1 flag (sync), rename the argument to flags, and explicitly define a WF_ space for individual flags. Signed-off-by: Peter Zijlstra LKML-Reference: Signed-off-by: Ingo Molnar