Re: [PATCH] pstore/zone: Emit registration message as a single pr_info()

[Kartik Rajput <kkartik@nvidia.com>]

Hi Kees,

Thanks for reviewing the patch!

On 24/04/26 21:03, Kees Cook wrote:
> External email: Use caution opening links or attachments
> 
> 
> On April 24, 2026 2:58:20 AM PDT, Kartik Rajput <kkartik@nvidia.com> wrote:
>> register_pstore_zone() prints its "registered ... as backend for ..."
>> summary as a pr_info() followed by several pr_cont() calls.
>>
>> pr_cont() is not atomic and has no log level of its own. It appends
>> to whichever line was most recently opened by a printk(). If a
>> pr_err() or pr_warn() from another CPU or an interrupt handler
>> preempts the pr_info() / pr_cont() sequence, it closes the
>> continuation between the fragments. This can cause parts of the
>> pstore registration message to appear at the wrong log level and be
>> interleaved with other messages.
>>
>> Furthermore, this causes the detection of new warning and error
>> messages in the kernel log to be unreliable.
>>
>> Format the registration line in a small local buffer using
>> scnprintf() and emit it with a single pr_info() call, making the
>> line atomic with respect to concurrent printk() callers.  No
>> functional change to registration.
>>
>> Signed-off-by: Kartik Rajput <kkartik@nvidia.com>
>> ---
>> fs/pstore/zone.c | 20 ++++++++++----------
>> 1 file changed, 10 insertions(+), 10 deletions(-)
>>
>> diff --git a/fs/pstore/zone.c b/fs/pstore/zone.c
>> index a3b003f9a3a0..fbe0a252dd2a 100644
>> --- a/fs/pstore/zone.c
>> +++ b/fs/pstore/zone.c
>> @@ -1301,6 +1301,8 @@ int register_pstore_zone(struct pstore_zone_info *info)
>> {
>>        int err = -EINVAL;
>>        struct psz_context *cxt = &pstore_zone_cxt;
>> +      char buf[256] = "";
>> +      size_t len = 0;
> 
> Please use a seq_buf backed by a stack array instead of the scnprintf calls.
> 
> Otherwise, yes, seems good to keep this all on one line.
> 
> Thanks!
> 
> -Kees
> 

ACK. I will push v2 to use seq_buf instead of scnprintf calls.

Thanks,
Kartik