[PATCH] scsi: qla2xxx: Format log strings only if needed

From: Roman Bolshakov <r.bolshakov@yadro.com>
To: "Martin K . Petersen" <martin.petersen@oracle.com>,
	<target-devel@vger.kernel.org>
Cc: <linux-scsi@vger.kernel.org>, <linux@yadro.com>,
	<GR-QLogic-Storage-Upstream@marvell.com>,
	Roman Bolshakov <r.bolshakov@yadro.com>,
	Rajan Shanmugavelu <rajan.shanmugavelu@oracle.com>,
	<stable@vger.kernel.org>
Subject: [PATCH] scsi: qla2xxx: Format log strings only if needed
Date: Fri, 12 Nov 2021 17:54:46 +0300	[thread overview]
Message-ID: <20211112145446.51210-1-r.bolshakov@yadro.com> (raw)

Commit 598a90f2002c4 ("scsi: qla2xxx: add ring buffer for tracing debug
logs") introduced unconditional log string formatting to ql_dbg() even
if ql_dbg_log event is disabled. It harms performance because some
strings are formatted in fastpath and/or interrupt context.

Cc: Rajan Shanmugavelu <rajan.shanmugavelu@oracle.com>
Cc: stable@vger.kernel.org
Fixes: 598a90f2002c4 ("scsi: qla2xxx: add ring buffer for tracing debug logs")
Signed-off-by: Roman Bolshakov <r.bolshakov@yadro.com>
---
 drivers/scsi/qla2xxx/qla_dbg.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/scsi/qla2xxx/qla_dbg.c b/drivers/scsi/qla2xxx/qla_dbg.c
index 25549a8a2d72..7cf1f78cbaee 100644
--- a/drivers/scsi/qla2xxx/qla_dbg.c
+++ b/drivers/scsi/qla2xxx/qla_dbg.c
@@ -2491,6 +2491,9 @@ ql_dbg(uint level, scsi_qla_host_t *vha, uint id, const char *fmt, ...)
 	struct va_format vaf;
 	char pbuf[64];
 
+	if (!ql_mask_match(level) && !trace_ql_dbg_log_enabled())
+		return;
+
 	va_start(va, fmt);
 
 	vaf.fmt = fmt;
-- 
2.33.1

