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| author |   Davidlohr Bueso <dave@stgolabs.net> | 2022-05-06 12:57:55 +0200 |
|---|---|---|
| committer |   Martin K. Petersen <martin.petersen@oracle.com> | 2022-05-16 21:26:50 -0400 |
| commit | 848b89778ed53e6c9f9e3ed01c90109ee970b3d1 (patch) | |
| tree | c4f3b92ebc65dba74b7e049a3e89f49b582ee43c | |
| parent | scsi: target: iscsi: Rename iscsi_session to iscsit_session (diff) | |
| download | linux-dev-848b89778ed53e6c9f9e3ed01c90109ee970b3d1.tar.xz linux-dev-848b89778ed53e6c9f9e3ed01c90109ee970b3d1.zip | |
scsi: fcoe: Add a local_lock to fcoe_percpu
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>
| -rw-r--r-- | drivers/scsi/fcoe/fcoe.c | 6 | ||||
| -rw-r--r-- | 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; }; /** |