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Message-ID: <fc2ddce7-d5f7-b9ce-3413-b6ffa87a7251@redhat.com>
Date: Fri, 28 Jan 2022 15:48:46 -0500
From: John Meneghini <jmeneghi@...hat.com>
To: "Martin K. Petersen" <martin.petersen@...cle.com>
Cc: Nilesh Javali <njavali@...vell.com>,
"linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
GR-QLogic-Storage-Upstream <GR-QLogic-Storage-Upstream@...vell.com>,
Saurav Kashyap <skashyap@...vell.com>,
"mlombard@...hat.com" <mlombard@...hat.com>,
"guazhang@...hat.com" <guazhang@...hat.com>
Subject: Re: [EXT] [PATCH] scsi: bnx2fc: make bnx2fc_recv_frame mp safe
Thanks.
Martin, is it too late to get this into staging for v5.17-rc2?
Please merge this patch.
/John
On 1/27/22 00:13, Saurav Kashyap wrote:
> Hi John,
>
>> -----Original Message-----
>> From: John Meneghini <jmeneghi@...hat.com>
>> Sent: Monday, January 24, 2022 8:21 PM
>> To: Saurav Kashyap <skashyap@...vell.com>
>> Cc: Nilesh Javali <njavali@...vell.com>; linux-scsi@...r.kernel.org; linux-
>> kernel@...r.kernel.org; GR-QLogic-Storage-Upstream <GR-QLogic-Storage-
>> Upstream@...vell.com>; mlombard@...hat.com; guazhang@...hat.com
>> 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@...hat.com>
>> Signed-off-by: John Meneghini <jmeneghi@...hat.com>
>> ---
>> 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@...vell.com>
>
>> 2.27.0
>
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