[PATCH 5.16 098/126] scsi: bnx2fc: Make bnx2fc_recv_frame() mp safe

Greg Kroah-Hartman
2022-02-07T12:03:28Z

From: John Meneghini <jmeneghi@redhat.com>

commit 936bd03405fc83ba039d42bc93ffd4b88418f1d3 upstream.

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

Restore the old get_cpu/put_cpu code with some modifications to reduce the
size of the critical section.

Link: https://lore.kernel.org/r/20220124145110.442335-1-jmeneghi@redhat.com
Fixes: d576a5e80cd0 ("bnx2fc: Improve stats update mechanism")
Tested-by: Guangwu Zhang <guazhang@redhat.com>
Acked-by: Saurav Kashyap <skashyap@marvell.com>
Signed-off-by: John Meneghini <jmeneghi@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/scsi/bnx2fc/bnx2fc_fcoe.c | 21 +++++++++++++--------
1 file changed, 13 insertions(+), 8 deletions(-)

--- 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 *ar

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_
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_
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;
}