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Message-Id: <1353377222-19541-1-git-send-email-dbasehore@chromium.org> Date: Mon, 19 Nov 2012 18:07:01 -0800 From: Derek Basehore <dbasehore@...omium.org> To: linux-kernel@...r.kernel.org Cc: axboe@...nel.dk, msb@...omium.orq, bleung@...omium.org, taysom@...omium.org, Derek Basehore <dbasehore@...omium.org> Subject: [PATCH v2 1/2] block: Remove deadlock in disk_clear_events In disk_clear_events, do not put work on system_nrt_freezable_wq. Instead, put it on system_nrt_wq. There is a race between probing a usb and suspending the device. Since probing a usb calls disk_clear_events, which puts work on a frozen workqueue, probing cannot finish after the workqueue is frozen. However, suspending cannot finish until the usb probe is finished, so we get a deadlock. Signed-off-by: Derek Basehore <dbasehore@...omium.org> Reviewed-by: Mandeep Singh Baines <msb@...omium.org> --- block/genhd.c | 8 +++++++- 1 files changed, 7 insertions(+), 1 deletions(-) diff --git a/block/genhd.c b/block/genhd.c index 6cace66..4e700ee 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -1571,7 +1571,13 @@ unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask) /* uncondtionally schedule event check and wait for it to finish */ disk_block_events(disk); - queue_delayed_work(system_freezable_wq, &ev->dwork, 0); + /* We need to put the work on system_nrt_wq here since there is a + * deadlock that happens while probing a usb device while suspending. If + * we put work on a freezable worqueue here, a usb probe will wait here + * until the workqueue is unfrozen during suspend. Since suspend waits + * on all probes to complete, we have a deadlock + */ + queue_delayed_work(system_nrt_wq, &ev->dwork, 0); flush_delayed_work(&ev->dwork); __disk_unblock_events(disk, false); -- 1.7.7.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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