Hi John,
> -----Original Message-----
> From: John Meneghini <jmeneghi@xxxxxxxxxx>
> Sent: Monday, January 24, 2022 8:21 PM
> To: Saurav Kashyap <skashyap@xxxxxxxxxxx>
> Cc: Nilesh Javali <njavali@xxxxxxxxxxx>; linux-scsi@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; GR-QLogic-Storage-Upstream <GR-QLogic-Storage-
> Upstream@xxxxxxxxxxx>; mlombard@xxxxxxxxxx; guazhang@xxxxxxxxxx
> Subject: [EXT] [PATCH] scsi: bnx2fc: make bnx2fc_recv_frame mp safe
>
> External Email
>
> ----------------------------------------------------------------------
> Running tests with a debug kernel shows that bnx2fc_recv_frame is
> modifying the per_cpu lport stats counters in a non-mpsafe way.
> Just boot a debug kernel and run the bnx2fc driver with the hardware
> enabled.
>
> [ 1391.699147] BUG: using smp_processor_id() in preemptible [00000000]
> code: bnx2fc_
> [ 1391.699160] caller is bnx2fc_recv_frame+0xbf9/0x1760 [bnx2fc]
> [ 1391.699174] CPU: 2 PID: 4355 Comm: bnx2fc_l2_threa Kdump: loaded
> Tainted: G B
> [ 1391.699180] Hardware name: HP ProLiant DL120 G7, BIOS J01
> 07/01/2013
> [ 1391.699183] Call Trace:
> [ 1391.699188] dump_stack_lvl+0x57/0x7d
> [ 1391.699198] check_preemption_disabled+0xc8/0xd0
> [ 1391.699205] bnx2fc_recv_frame+0xbf9/0x1760 [bnx2fc]
> [ 1391.699215] ? do_raw_spin_trylock+0xb5/0x180
> [ 1391.699221] ? bnx2fc_npiv_create_vports.isra.0+0x4e0/0x4e0 [bnx2fc]
> [ 1391.699229] ? bnx2fc_l2_rcv_thread+0xb7/0x3a0 [bnx2fc]
> [ 1391.699240] bnx2fc_l2_rcv_thread+0x1af/0x3a0 [bnx2fc]
> [ 1391.699250] ? bnx2fc_ulp_init+0xc0/0xc0 [bnx2fc]
> [ 1391.699258] kthread+0x364/0x420
> [ 1391.699263] ? _raw_spin_unlock_irq+0x24/0x50
> [ 1391.699268] ? set_kthread_struct+0x100/0x100
> [ 1391.699273] ret_from_fork+0x22/0x30
>
> To fix the problem: restore the old get_cpu/put_cpu code with some
> modifications to reduce the size of the critical section.
>
> Fixes: d576a5e80cd0 ("bnx2fc: Improve stats update mechanism")
> Tested-by: Guangwu Zhang <guazhang@xxxxxxxxxx>
> Signed-off-by: John Meneghini <jmeneghi@xxxxxxxxxx>
> ---
> drivers/scsi/bnx2fc/bnx2fc_fcoe.c | 21 +++++++++++++--------
> 1 file changed, 13 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
> b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
> index 71fa62bd3083..e41a94dc2d1f 100644
> --- a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
> +++ b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
> @@ -508,7 +508,8 @@ static int bnx2fc_l2_rcv_thread(void *arg)
>
> static void bnx2fc_recv_frame(struct sk_buff *skb)
> {
> - u32 fr_len;
> + u64 crc_err;
> + u32 fr_len, fr_crc;
> struct fc_lport *lport;
> struct fcoe_rcv_info *fr;
> struct fc_stats *stats;
> @@ -542,6 +543,11 @@ static void bnx2fc_recv_frame(struct sk_buff *skb)
> skb_pull(skb, sizeof(struct fcoe_hdr));
> fr_len = skb->len - sizeof(struct fcoe_crc_eof);
>
> + stats = per_cpu_ptr(lport->stats, get_cpu());
> + stats->RxFrames++;
> + stats->RxWords += fr_len / FCOE_WORD_TO_BYTE;
> + put_cpu();
> +
> fp = (struct fc_frame *)skb;
> fc_frame_init(fp);
> fr_dev(fp) = lport;
> @@ -624,16 +630,15 @@ static void bnx2fc_recv_frame(struct sk_buff *skb)
> return;
> }
>
> - stats = per_cpu_ptr(lport->stats, smp_processor_id());
> - stats->RxFrames++;
> - stats->RxWords += fr_len / FCOE_WORD_TO_BYTE;
> + fr_crc = le32_to_cpu(fr_crc(fp));
>
> - if (le32_to_cpu(fr_crc(fp)) !=
> - ~crc32(~0, skb->data, fr_len)) {
> - if (stats->InvalidCRCCount < 5)
> + if (unlikely(fr_crc != ~crc32(~0, skb->data, fr_len))) {
> + stats = per_cpu_ptr(lport->stats, get_cpu());
> + crc_err = (stats->InvalidCRCCount++);
> + put_cpu();
> + if (crc_err < 5)
> printk(KERN_WARNING PFX "dropping frame with "
> "CRC error\n");
> - stats->InvalidCRCCount++;
> kfree_skb(skb);
> return;
> }
> --
Thanks for the patch.
Acked-by: Saurav Kashyap <skashyap@xxxxxxxxxxx>
> 2.27.0
