diff mbox series

scsi: bnx2fc: make bnx2fc_recv_frame mp safe

Message ID 20220124145110.442335-1-jmeneghi@redhat.com (mailing list archive)
State Accepted
Headers show
Series scsi: bnx2fc: make bnx2fc_recv_frame mp safe | expand

Commit Message

John Meneghini Jan. 24, 2022, 2:51 p.m. UTC
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@redhat.com>
Signed-off-by: John Meneghini <jmeneghi@redhat.com>
---
 drivers/scsi/bnx2fc/bnx2fc_fcoe.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

Comments

John Meneghini Jan. 25, 2022, 5:32 p.m. UTC | #1
Can I please get a review and approval for this patch?

I'd like this to get into v5.17-rc2

Thanks,

/John


On 1/24/22 09:51, John Meneghini wrote:
>      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@redhat.com>
> Signed-off-by: John Meneghini <jmeneghi@redhat.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;
>   	}
Saurav Kashyap Jan. 27, 2022, 5:13 a.m. UTC | #2
Hi John,

> -----Original Message-----
> From: John Meneghini <jmeneghi@redhat.com>
> Sent: Monday, January 24, 2022 8:21 PM
> To: Saurav Kashyap <skashyap@marvell.com>
> Cc: Nilesh Javali <njavali@marvell.com>; linux-scsi@vger.kernel.org; linux-
> kernel@vger.kernel.org; GR-QLogic-Storage-Upstream <GR-QLogic-Storage-
> Upstream@marvell.com>; mlombard@redhat.com; guazhang@redhat.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@redhat.com>
> Signed-off-by: John Meneghini <jmeneghi@redhat.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@marvell.com>

> 2.27.0
John Meneghini Jan. 28, 2022, 8:48 p.m. UTC | #3
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@redhat.com>
>> Sent: Monday, January 24, 2022 8:21 PM
>> To: Saurav Kashyap <skashyap@marvell.com>
>> Cc: Nilesh Javali <njavali@marvell.com>; linux-scsi@vger.kernel.org; linux-
>> kernel@vger.kernel.org; GR-QLogic-Storage-Upstream <GR-QLogic-Storage-
>> Upstream@marvell.com>; mlombard@redhat.com; guazhang@redhat.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@redhat.com>
>> Signed-off-by: John Meneghini <jmeneghi@redhat.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@marvell.com>
> 
>> 2.27.0
>
Martin K. Petersen Jan. 31, 2022, 5:37 p.m. UTC | #4
John,

Applied to 5.18/scsi-staging, thanks!

Please make sure your commit descriptions are left aligned:

>     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.
 ^^^^^
Martin K. Petersen Jan. 31, 2022, 5:40 p.m. UTC | #5
John,

Erm. Hit the wrong key. Applied to 5.17/scsi-fixes, of course.

> Martin, is it too late to get this into staging for v5.17-rc2?

Patches sit in linux-next for about a week before they get sent to
Linus.
Martin K. Petersen Feb. 1, 2022, 2:03 a.m. UTC | #6
On Mon, 24 Jan 2022 09:51:10 -0500, John Meneghini wrote:

>     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
> 
> [...]

Applied to 5.17/scsi-fixes, thanks!

[1/1] scsi: bnx2fc: make bnx2fc_recv_frame mp safe
      https://git.kernel.org/mkp/scsi/c/936bd03405fc
diff mbox series

Patch

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;
 	}