From: Davidlohr Bueso <dave@stgolabs.net>
Date: Fri, 6 May 2022 12:57:55 +0200
Subject: [PATCH] scsi: fcoe: Add a local_lock to fcoe_percpu
Git-commit: 848b89778ed53e6c9f9e3ed01c90109ee970b3d1
Patch-mainline: v5.19-rc1
References: jsc#PED-1559
fcoe_get_paged_crc_eof() relies on the caller having preemption disabled to
ensure the per-CPU fcoe_percpu context remains valid throughout the
call. This is done by either holding spinlocks (such as bnx2fc_global_lock
or qedf_global_lock) or the get_cpu() from fcoe_alloc_paged_crc_eof(). This
last one breaks PREEMPT_RT semantics as there can be memory allocation and
end up sleeping in atomic contexts.
Introduce a local_lock_t to struct fcoe_percpu that will keep the non-RT
case the same, mapping to preempt_disable/enable, while RT will use a
per-CPU spinlock allowing the region to be preemptible but still maintain
CPU locality. The other users of fcoe_percpu are already safe in this
regard and do not require local_lock()ing.
Link: https://lore.kernel.org/r/20211117025956.79616-3-dave@stgolabs.net
Link: https://lore.kernel.org/r/20220506105758.283887-2-bigeasy@linutronix.de
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Hannes Reinecke <hare@suse.com>
---
drivers/scsi/fcoe/fcoe.c | 6 ++++--
include/scsi/libfcoe.h | 2 ++
2 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c
index 983e00135fea..af9b788823ac 100644
--- a/drivers/scsi/fcoe/fcoe.c
+++ b/drivers/scsi/fcoe/fcoe.c
@@ -1453,9 +1453,10 @@ static int fcoe_alloc_paged_crc_eof(struct sk_buff *skb, int tlen)
struct fcoe_percpu_s *fps;
int rc;
- fps = &get_cpu_var(fcoe_percpu);
+ local_lock(&fcoe_percpu.lock);
+ fps = this_cpu_ptr(&fcoe_percpu);
rc = fcoe_get_paged_crc_eof(skb, tlen, fps);
- put_cpu_var(fcoe_percpu);
+ local_unlock(&fcoe_percpu.lock);
return rc;
}
@@ -2488,6 +2489,7 @@ static int __init fcoe_init(void)
p = per_cpu_ptr(&fcoe_percpu, cpu);
INIT_WORK(&p->work, fcoe_receive_work);
skb_queue_head_init(&p->fcoe_rx_list);
+ local_lock_init(&p->lock);
}
/* Setup link change notification */
diff --git a/include/scsi/libfcoe.h b/include/scsi/libfcoe.h
index fac8e89aed81..6e79fb87fea2 100644
--- a/include/scsi/libfcoe.h
+++ b/include/scsi/libfcoe.h
@@ -14,6 +14,7 @@
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/workqueue.h>
+#include <linux/local_lock.h>
#include <linux/random.h>
#include <scsi/fc/fc_fcoe.h>
#include <scsi/libfc.h>
@@ -326,6 +327,7 @@ struct fcoe_percpu_s {
struct sk_buff_head fcoe_rx_list;
struct page *crc_eof_page;
int crc_eof_offset;
+ local_lock_t lock;
};
/**
--
2.35.3