Re: [PATCH] block: ratelimite pr_err on IO path

[Jinpu Wang]

On Wed, Apr 11, 2018 at 7:07 PM, Elliott, Robert (Persistent Memory)
<elli...@hpe.com> wrote:
>> -Original Message-
>> From: linux-kernel-ow...@vger.kernel.org [mailto:linux-kernel-
>> ow...@vger.kernel.org] On Behalf Of Jack Wang
>> Sent: Wednesday, April 11, 2018 8:21 AM
>> Subject: [PATCH] block: ratelimite pr_err on IO path
>>
>> From: Jack Wang <jinpu.w...@profitbricks.com>
> ...
>> - pr_err("%s: ref tag error at location %llu " \
>> -"(rcvd %u)\n", iter->disk_name,
>> -(unsigned long long)
>> -iter->seed, be32_to_cpu(pi->ref_tag));
>> + pr_err_ratelimited("%s: ref tag error at "
>> +"location %llu (rcvd %u)\n",
>
> Per process/coding-style.rst, you should keep a string like that on
> one line even if that exceeds 80 columns:
>
>   Statements longer than 80 columns will be broken into sensible chunks, 
> unless
>   exceeding 80 columns significantly increases readability and does not hide
>   information. ... However, never break user-visible strings such as
>   printk messages, because that breaks the ability to grep for them.
>
>
Thanks Robert, as the original code keep the 80 columns, I just
followed, I will fix it in v2.


-- 
Jack Wang
Linux Kernel Developer

ProfitBricks GmbH
Greifswalder Str. 207
D - 10405 Berlin

RE: [PATCH] block: ratelimite pr_err on IO path

[Elliott, Robert (Persistent Memory)]

> -Original Message-
> From: linux-kernel-ow...@vger.kernel.org [mailto:linux-kernel-
> ow...@vger.kernel.org] On Behalf Of Jack Wang
> Sent: Wednesday, April 11, 2018 8:21 AM
> Subject: [PATCH] block: ratelimite pr_err on IO path
> 
> From: Jack Wang <jinpu.w...@profitbricks.com>
...
> - pr_err("%s: ref tag error at location %llu " \
> -"(rcvd %u)\n", iter->disk_name,
> -(unsigned long long)
> -iter->seed, be32_to_cpu(pi->ref_tag));
> + pr_err_ratelimited("%s: ref tag error at "
> +"location %llu (rcvd %u)\n",

Per process/coding-style.rst, you should keep a string like that on
one line even if that exceeds 80 columns:

  Statements longer than 80 columns will be broken into sensible chunks, unless
  exceeding 80 columns significantly increases readability and does not hide
  information. ... However, never break user-visible strings such as
  printk messages, because that breaks the ability to grep for them.

[PATCH] block: ratelimite pr_err on IO path

[Jack Wang]

From: Jack Wang 

This avoid soft lockup below:
[ 2328.328429] Call Trace:
[ 2328.328433]  vprintk_emit+0x229/0x2e0
[ 2328.328436]  ? t10_pi_type3_verify_ip+0x20/0x20
[ 2328.328437]  printk+0x52/0x6e
[ 2328.328439]  t10_pi_verify+0x9e/0xf0
[ 2328.328441]  bio_integrity_process+0x12e/0x220
[ 2328.328442]  ? t10_pi_type1_verify_crc+0x20/0x20
[ 2328.328443]  bio_integrity_verify_fn+0xde/0x140
[ 2328.328447]  process_one_work+0x13f/0x370
[ 2328.328449]  worker_thread+0x62/0x3d0
[ 2328.328450]  ? rescuer_thread+0x2f0/0x2f0
[ 2328.328452]  kthread+0x116/0x150
[ 2328.328454]  ? __kthread_parkme+0x70/0x70
[ 2328.328457]  ret_from_fork+0x35/0x40

Signed-off-by: Jack Wang 
---
 block/t10-pi.c | 20 
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/block/t10-pi.c b/block/t10-pi.c
index a98db38..35967d5 100644
--- a/block/t10-pi.c
+++ b/block/t10-pi.c
@@ -84,10 +84,12 @@ static blk_status_t t10_pi_verify(struct blk_integrity_iter 
*iter,
 
if (be32_to_cpu(pi->ref_tag) !=
lower_32_bits(iter->seed)) {
-   pr_err("%s: ref tag error at location %llu " \
-  "(rcvd %u)\n", iter->disk_name,
-  (unsigned long long)
-  iter->seed, be32_to_cpu(pi->ref_tag));
+   pr_err_ratelimited("%s: ref tag error at "
+  "location %llu (rcvd %u)\n",
+  iter->disk_name,
+  (unsigned long long)
+  iter->seed,
+  be32_to_cpu(pi->ref_tag));
return BLK_STS_PROTECTION;
}
break;
@@ -101,10 +103,12 @@ static blk_status_t t10_pi_verify(struct 
blk_integrity_iter *iter,
csum = fn(iter->data_buf, iter->interval);
 
if (pi->guard_tag != csum) {
-   pr_err("%s: guard tag error at sector %llu " \
-  "(rcvd %04x, want %04x)\n", iter->disk_name,
-  (unsigned long long)iter->seed,
-  be16_to_cpu(pi->guard_tag), be16_to_cpu(csum));
+   pr_err_ratelimited("%s: guard tag error at sector %llu "
+  "(rcvd %04x, want %04x)\n",
+  iter->disk_name,
+  (unsigned long long)iter->seed,
+  be16_to_cpu(pi->guard_tag),
+  be16_to_cpu(csum));
return BLK_STS_PROTECTION;
}
 
-- 
2.7.4