Commit 8e782623 authored by Matthew R. Ochs's avatar Matthew R. Ochs Committed by James Bottomley

cxlflash: Fix to prevent EEH recovery failure

The process_sense() routine can perform a read capacity which
can take some time to complete. If an EEH occurs while waiting
on the read capacity, the EEH handler will wait to obtain the
context's mutex in order to put the context in an error state.
The EEH handler will sit and wait until the context is free,
but this wait can potentially last forever (deadlock) if the
scsi_execute() that performs the read capacity experiences a
timeout and calls into the reset callback. When that occurs,
the reset callback sees that the device is already being reset
and waits for the reset to complete. This leaves two threads
waiting on the other.

To address this issue, make the context unavailable to new,
non-system owned threads and release the context while calling
into process_sense(). After returning from process_sense() the
context mutex is reacquired and the context is made available
again. The context can be safely moved to the error state if
needed during the unavailable window as no other threads will
hold its reference.
Signed-off-by: default avatarMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: default avatarManoj N. Kumar <manoj@linux.vnet.ibm.com>
Reviewed-by: default avatarBrian King <brking@linux.vnet.ibm.com>
Reviewed-by: default avatarDaniel Axtens <dja@axtens.net>
Reviewed-by: default avatarTomas Henzl <thenzl@redhat.com>
Signed-off-by: default avatarJames Bottomley <JBottomley@Odin.com>
parent 1786f4a0
...@@ -1787,12 +1787,21 @@ static int cxlflash_disk_verify(struct scsi_device *sdev, ...@@ -1787,12 +1787,21 @@ static int cxlflash_disk_verify(struct scsi_device *sdev,
* inquiry (i.e. the Unit attention is due to the WWN changing). * inquiry (i.e. the Unit attention is due to the WWN changing).
*/ */
if (verify->hint & DK_CXLFLASH_VERIFY_HINT_SENSE) { if (verify->hint & DK_CXLFLASH_VERIFY_HINT_SENSE) {
/* Can't hold mutex across process_sense/read_cap16,
* since we could have an intervening EEH event.
*/
ctxi->unavail = true;
mutex_unlock(&ctxi->mutex);
rc = process_sense(sdev, verify); rc = process_sense(sdev, verify);
if (unlikely(rc)) { if (unlikely(rc)) {
dev_err(dev, "%s: Failed to validate sense data (%d)\n", dev_err(dev, "%s: Failed to validate sense data (%d)\n",
__func__, rc); __func__, rc);
mutex_lock(&ctxi->mutex);
ctxi->unavail = false;
goto out; goto out;
} }
mutex_lock(&ctxi->mutex);
ctxi->unavail = false;
} }
switch (gli->mode) { switch (gli->mode) {
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment