scsi/scsi_error: Use call_rcu_flush() instead of call_rcu()

urezki · chantra · commit 0f1b63260945 · 2022-10-19T23:22:13.000-07:00
Slow boot time is seen on KVM running typical Linux distributions due to
SCSI layer calling call_rcu(). Recent changes to save power may be
causing this slowness. Using call_rcu_flush() fixes the issue and brings
the boot time back to what it originally was. Convert it.

Tested-by: Joel Fernandes (Google) &lt;joel@joelfernandes.org&gt;
Signed-off-by: Uladzislau Rezki &lt;urezki@gmail.com&gt;
Signed-off-by: Joel Fernandes (Google) &lt;joel@joelfernandes.org&gt;
Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
@@ -312,7 +312,7 @@ void scsi_eh_scmd_add(struct scsi_cmnd *scmd)
 	 * Ensure that all tasks observe the host state change before the
 	 * host_failed change.
 	 */
-	call_rcu(&scmd->rcu, scsi_eh_inc_host_failed);
+	call_rcu_flush(&scmd->rcu, scsi_eh_inc_host_failed);
 }
 
 /**

Original file line number	Diff line number	Diff line change
`@@ -312,7 +312,7 @@ void scsi_eh_scmd_add(struct scsi_cmnd *scmd)`
`312`	`312`	`* Ensure that all tasks observe the host state change before the`
`313`	`313`	`* host_failed change.`
`314`	`314`	`*/`
`315`		`- call_rcu(&scmd->rcu, scsi_eh_inc_host_failed);`
	`315`	`+ call_rcu_flush(&scmd->rcu, scsi_eh_inc_host_failed);`
`316`	`316`	`}`
`317`	`317`
`318`	`318`	`/**`