diff options
| -rw-r--r-- | drivers/ata/libata-scsi.c | 21 | ||||
| -rw-r--r-- | kernel/freezer.c | 6 |
2 files changed, 27 insertions, 0 deletions
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c index db6dfcfa3e2e..176f62950e3d 100644 --- a/drivers/ata/libata-scsi.c +++ b/drivers/ata/libata-scsi.c @@ -3871,6 +3871,27 @@ void ata_scsi_hotplug(struct work_struct *work) return; } + /* + * XXX - UGLY HACK + * + * The block layer suspend/resume path is fundamentally broken due + * to freezable kthreads and workqueue and may deadlock if a block + * device gets removed while resume is in progress. I don't know + * what the solution is short of removing freezable kthreads and + * workqueues altogether. + * + * The following is an ugly hack to avoid kicking off device + * removal while freezer is active. This is a joke but does avoid + * this particular deadlock scenario. + * + * https://bugzilla.kernel.org/show_bug.cgi?id=62801 + * http://marc.info/?l=linux-kernel&m=138695698516487 + */ +#ifdef CONFIG_FREEZER + while (pm_freezing) + msleep(10); +#endif + DPRINTK("ENTER\n"); mutex_lock(&ap->scsi_scan_mutex); diff --git a/kernel/freezer.c b/kernel/freezer.c index b462fa197517..aa6a8aadb911 100644 --- a/kernel/freezer.c +++ b/kernel/freezer.c @@ -19,6 +19,12 @@ EXPORT_SYMBOL(system_freezing_cnt); bool pm_freezing; bool pm_nosig_freezing; +/* + * Temporary export for the deadlock workaround in ata_scsi_hotplug(). + * Remove once the hack becomes unnecessary. + */ +EXPORT_SYMBOL_GPL(pm_freezing); + /* protects freezing and frozen transitions */ static DEFINE_SPINLOCK(freezer_lock); |