scsi: cxlflash: Prevent deadlock when adapter probe fails

vaibhav92 · martinkpetersen · commit bb61b843ffd4 · 2019-02-04T22:24:02.000-05:00
Presently when an error is encountered during probe of the cxlflash adapter, a deadlock is seen with cpu thread stuck inside cxlflash_remove(). Below is the trace of the deadlock as logged by khungtaskd: cxlflash 0006:00:00.0: cxlflash_probe: init_afu failed rc=-16 INFO: task kworker/80:1:890 blocked for more than 120 seconds. Not tainted 5.0.0-rc4-capi2-kexec+ #2 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/80:1 D 0 890 2 0x00000808 Workqueue: events work_for_cpu_fn Call Trace: 0x4d72136320 (unreliable) __switch_to+0x2cc/0x460 __schedule+0x2bc/0xac0 schedule+0x40/0xb0 cxlflash_remove+0xec/0x640 [cxlflash] cxlflash_probe+0x370/0x8f0 [cxlflash] local_pci_probe+0x6c/0x140 work_for_cpu_fn+0x38/0x60 process_one_work+0x260/0x530 worker_thread+0x280/0x5d0 kthread+0x1a8/0x1b0 ret_from_kernel_thread+0x5c/0x80 INFO: task systemd-udevd:5160 blocked for more than 120 seconds. The deadlock occurs as cxlflash_remove() is called from cxlflash_probe() without setting 'cxlflash_cfg->state' to STATE_PROBED and the probe thread starts to wait on 'cxlflash_cfg->reset_waitq'. Since the device was never successfully probed the 'cxlflash_cfg->state' never changes from STATE_PROBING hence the deadlock occurs. We fix this deadlock by setting the variable 'cxlflash_cfg->state' to STATE_PROBED in case an error occurs during cxlflash_probe() and just before calling cxlflash_remove(). Cc: stable@vger.kernel.org Fixes: c21e0bb("cxlflash: Base support for IBM CXL Flash Adapter") Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
diff --git a/drivers/scsi/cxlflash/main.c b/drivers/scsi/cxlflash/main.c
@@ -3687,6 +3687,7 @@ static int cxlflash_probe(struct pci_dev *pdev,
 	host->max_cmd_len = CXLFLASH_MAX_CDB_LEN;
 
 	cfg = shost_priv(host);
+	cfg->state = STATE_PROBING;
 	cfg->host = host;
 	rc = alloc_mem(cfg);
 	if (rc) {
@@ -3775,6 +3776,7 @@ static int cxlflash_probe(struct pci_dev *pdev,
 	return rc;
 
 out_remove:
+	cfg->state = STATE_PROBED;
 	cxlflash_remove(pdev);
 	goto out;
 }
