libata, freezer: avoid block device removal while system is frozen

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / drivers / ata / libata-scsi.c

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 4abdbdff6943454552fa3bf509a8bb4a70dc67bb..81a353590b8a2c3424b2811cb69a0e1137300ada 100644 (file)
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3864,6 +3864,27 @@ 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);