| Message ID | 20130701151712.f453745bc0c587f449cc3214@linux-foundation.org (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On Mon, 2013-07-01 at 15:17 -0700, Andrew Morton wrote: > On Mon, 1 Jul 2013 20:58:35 +0530 Sujit Reddy Thumma <sthumma@codeaurora.org> wrote: > > > When block runtime PM is enabled following warning is seen > > while resuming the device. > > > > BUG: sleeping function called from invalid context at > > .../drivers/base/power/runtime.c:923 > > in_atomic(): 1, irqs_disabled(): 128, pid: 12, name: kworker/0:1 > > [<c0014448>] (unwind_backtrace+0x0/0x120) from > > [<c03120e4>] (__pm_runtime_suspend+0x34/0xa0) from > > [<c021c33c>] (blk_post_runtime_resume+0x4c/0x5c) from > > [<c03297cc>] (scsi_runtime_resume+0x90/0xb4) from > > [<c0310940>] (__rpm_callback+0x30/0x58) from > > [<c0310980>] (rpm_callback+0x18/0x28) from > > [<c0311ab0>] (rpm_resume+0x3dc/0x540) from > > [<c03120a4>] (pm_runtime_work+0x8c/0x98) from > > [<c007767c>] (process_one_work+0x238/0x3e4) from > > [<c0077b90>] (worker_thread+0x1ac/0x2ac) from > > [<c007cfdc>] (kthread+0x88/0x94) from > > [<c000ece0>] (kernel_thread_exit+0x0/0x8) > > > > Fix this by releasing spin_lock_irq() before calling > > pm_runtime_autosuspend() in blk_post_runtime_resume(). > > > > --- a/block/blk-core.c > > +++ b/block/blk-core.c > > @@ -3159,16 +3159,18 @@ EXPORT_SYMBOL(blk_pre_runtime_resume); > > */ > > void blk_post_runtime_resume(struct request_queue *q, int err) > > { > > - spin_lock_irq(q->queue_lock); > > if (!err) { > > + spin_lock_irq(q->queue_lock); > > q->rpm_status = RPM_ACTIVE; > > __blk_run_queue(q); > > pm_runtime_mark_last_busy(q->dev); > > + spin_unlock_irq(q->queue_lock); > > pm_runtime_autosuspend(q->dev); > > } else { > > + spin_lock_irq(q->queue_lock); > > q->rpm_status = RPM_SUSPENDED; > > + spin_unlock_irq(q->queue_lock); > > } > > - spin_unlock_irq(q->queue_lock); > > } > > EXPORT_SYMBOL(blk_post_runtime_resume); > > #endif > > I suppose we can do this cleanly enough: > > --- a/block/blk-core.c~block-fix-possible-sleep-in-invalid-context-fix > +++ a/block/blk-core.c > @@ -3159,15 +3159,14 @@ EXPORT_SYMBOL(blk_pre_runtime_resume); > */ > void blk_post_runtime_resume(struct request_queue *q, int err) > { > + spin_lock_irq(q->queue_lock); > if (!err) { > - spin_lock_irq(q->queue_lock); > q->rpm_status = RPM_ACTIVE; > __blk_run_queue(q); > pm_runtime_mark_last_busy(q->dev); > spin_unlock_irq(q->queue_lock); > pm_request_autosuspend(q->dev); > } else { > - spin_lock_irq(q->queue_lock); > q->rpm_status = RPM_SUSPENDED; > spin_unlock_irq(q->queue_lock); > } > _ > > > I wonder if we actually need locking around that second write to > q->rpm_status. Shouldn't: it's an int, which makes it a 32 bit quantity we believe to have atomic write properties on every platform. James -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, 01 Jul 2013 15:24:11 -0700 James Bottomley <James.Bottomley@hansenpartnership.com> wrote: > > --- a/block/blk-core.c~block-fix-possible-sleep-in-invalid-context-fix > > +++ a/block/blk-core.c > > @@ -3159,15 +3159,14 @@ EXPORT_SYMBOL(blk_pre_runtime_resume); > > */ > > void blk_post_runtime_resume(struct request_queue *q, int err) > > { > > + spin_lock_irq(q->queue_lock); > > if (!err) { > > - spin_lock_irq(q->queue_lock); > > q->rpm_status = RPM_ACTIVE; > > __blk_run_queue(q); > > pm_runtime_mark_last_busy(q->dev); > > spin_unlock_irq(q->queue_lock); > > pm_request_autosuspend(q->dev); > > } else { > > - spin_lock_irq(q->queue_lock); > > q->rpm_status = RPM_SUSPENDED; > > spin_unlock_irq(q->queue_lock); > > } > > _ > > > > > > I wonder if we actually need locking around that second write to > > q->rpm_status. > > Shouldn't: it's an int, which makes it a 32 bit quantity we believe to > have atomic write properties on every platform. Yes, but. If there's some other code path which does: spin_lock(queue_lock); x = q->rpm_status; ... y = q->rpm_status; ... <assumes x == y> spin_unlock(queue_lock); then it blows up if we make the suggested change. Stranger things have happened... -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
--- a/block/blk-core.c~block-fix-possible-sleep-in-invalid-context-fix +++ a/block/blk-core.c @@ -3159,15 +3159,14 @@ EXPORT_SYMBOL(blk_pre_runtime_resume); */ void blk_post_runtime_resume(struct request_queue *q, int err) { + spin_lock_irq(q->queue_lock); if (!err) { - spin_lock_irq(q->queue_lock); q->rpm_status = RPM_ACTIVE; __blk_run_queue(q); pm_runtime_mark_last_busy(q->dev); spin_unlock_irq(q->queue_lock); pm_request_autosuspend(q->dev); } else { - spin_lock_irq(q->queue_lock); q->rpm_status = RPM_SUSPENDED; spin_unlock_irq(q->queue_lock); }