linux-kernel - [PATCH AUTOSEL 5.13 07/88] scsi: lpfc: Remove use of kmalloc() in trace event logging

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Date:   Thu,  9 Sep 2021 20:16:59 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     James Smart <jsmart2021@...il.com>,
        Justin Tee <justin.tee@...adcom.com>,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        Sasha Levin <sashal@...nel.org>, linux-scsi@...r.kernel.org
Subject: [PATCH AUTOSEL 5.13 07/88] scsi: lpfc: Remove use of kmalloc() in trace event logging

From: James Smart <jsmart2021@...il.com>

[ Upstream commit e8613084053d406c22914385a488e8b85072100c ]

There are instances when trace event logs are triggered from an interrupt
context. The trace event log may attempt to alloc memory causing scheduling
while atomic bug call traces.

Remove the need for the kmalloc'ed vport array when checking the
log_verbose flag, which eliminates the need for any allocation.

Link: https://lore.kernel.org/r/20210707184351.67872-3-jsmart2021@gmail.com
Co-developed-by: Justin Tee <justin.tee@...adcom.com>
Signed-off-by: Justin Tee <justin.tee@...adcom.com>
Signed-off-by: James Smart <jsmart2021@...il.com>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/scsi/lpfc/lpfc_init.c | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/drivers/scsi/lpfc/lpfc_init.c b/drivers/scsi/lpfc/lpfc_init.c
index 697053aa2771..b661e95a8a36 100644
--- a/drivers/scsi/lpfc/lpfc_init.c
+++ b/drivers/scsi/lpfc/lpfc_init.c
@@ -14061,8 +14061,9 @@ void lpfc_dmp_dbg(struct lpfc_hba *phba)
 	unsigned int temp_idx;
 	int i;
 	int j = 0;
-	unsigned long rem_nsec;
-	struct lpfc_vport **vports;
+	unsigned long rem_nsec, iflags;
+	bool log_verbose = false;
+	struct lpfc_vport *port_iterator;
 
 	/* Don't dump messages if we explicitly set log_verbose for the
 	 * physical port or any vport.
@@ -14070,16 +14071,24 @@ void lpfc_dmp_dbg(struct lpfc_hba *phba)
 	if (phba->cfg_log_verbose)
 		return;
 
-	vports = lpfc_create_vport_work_array(phba);
-	if (vports != NULL) {
-		for (i = 0; i <= phba->max_vpi && vports[i] != NULL; i++) {
-			if (vports[i]->cfg_log_verbose) {
-				lpfc_destroy_vport_work_array(phba, vports);
+	spin_lock_irqsave(&phba->port_list_lock, iflags);
+	list_for_each_entry(port_iterator, &phba->port_list, listentry) {
+		if (port_iterator->load_flag & FC_UNLOADING)
+			continue;
+		if (scsi_host_get(lpfc_shost_from_vport(port_iterator))) {
+			if (port_iterator->cfg_log_verbose)
+				log_verbose = true;
+
+			scsi_host_put(lpfc_shost_from_vport(port_iterator));
+
+			if (log_verbose) {
+				spin_unlock_irqrestore(&phba->port_list_lock,
+						       iflags);
 				return;
 			}
 		}
 	}
-	lpfc_destroy_vport_work_array(phba, vports);
+	spin_unlock_irqrestore(&phba->port_list_lock, iflags);
 
 	if (atomic_cmpxchg(&phba->dbg_log_dmping, 0, 1) != 0)
 		return;
-- 
2.30.2