[PATCH 5.10 051/132] scsi: qla2xxx: Format log strings only if needed

Greg Kroah-Hartman
2021-12-13T09:56:18Z

From: Roman Bolshakov <r.bolshakov@yadro.com>

commit 69002c8ce914ef0ae22a6ea14b43bb30b9a9a6a8 upstream.

Commit 598a90f2002c ("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.

Link: https://lore.kernel.org/r/20211112145446.51210-1-r.bolshakov@yadro.com
Fixes: 598a90f2002c ("scsi: qla2xxx: add ring buffer for tracing debug logs")
Cc: Rajan Shanmugavelu <rajan.shanmugavelu@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: Roman Bolshakov <r.bolshakov@yadro.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/scsi/qla2xxx/qla_dbg.c | 3 +++
1 file changed, 3 insertions(+)

--- a/drivers/scsi/qla2xxx/qla_dbg.c
+++ b/drivers/scsi/qla2xxx/qla_dbg.c
@@ -2477,6 +2477,9 @@ ql_dbg(uint level, scsi_qla_host_t *vha,
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;