All of lore.kernel.org
 help / color / mirror / Atom feed
From: Michael Ellerman <mpe@ellerman.id.au>
To: Vaibhav Jain <vaibhav@linux.ibm.com>,
	linuxppc-dev@lists.ozlabs.org, linux-nvdimm@lists.01.org
Cc: Vaibhav Jain <vaibhav@linux.ibm.com>,
	"Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Subject: Re: [PATCH v2] powerpc/papr_scm: Fix warning triggered by perf_stats_show()
Date: Tue, 15 Sep 2020 21:30:08 +1000	[thread overview]
Message-ID: <87imcfp9a7.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <20200912081451.66225-1-vaibhav@linux.ibm.com>

Vaibhav Jain <vaibhav@linux.ibm.com> writes:
> A warning is reported by the kernel in case perf_stats_show() returns
> an error code. The warning is of the form below:
>
>  papr_scm ibm,persistent-memory:ibm,pmemory@44100001:
>  	  Failed to query performance stats, Err:-10
>  dev_attr_show: perf_stats_show+0x0/0x1c0 [papr_scm] returned bad count
>  fill_read_buffer: dev_attr_show+0x0/0xb0 returned bad count
>
> On investigation it looks like that the compiler is silently truncating the
> return value of drc_pmem_query_stats() from 'long' to 'int', since the
> variable used to store the return code 'rc' is an 'int'. This
> truncated value is then returned back as a 'ssize_t' back from
> perf_stats_show() to 'dev_attr_show()' which thinks of it as a large
> unsigned number and triggers this warning..
>
> To fix this we update the type of variable 'rc' from 'int' to
> 'ssize_t' that prevents the compiler from truncating the return value
> of drc_pmem_query_stats() and returning correct signed value back from
> perf_stats_show().
>
> Fixes: 2d02bf835e573 ('powerpc/papr_scm: Fetch nvdimm performance
>        stats from PHYP')

Please don't word wrap the Fixes tag it breaks b4.

I've fixed it up this time.

cheers
_______________________________________________
Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org
To unsubscribe send an email to linux-nvdimm-leave@lists.01.org

WARNING: multiple messages have this Message-ID (diff)
From: Michael Ellerman <mpe@ellerman.id.au>
To: Vaibhav Jain <vaibhav@linux.ibm.com>,
	linuxppc-dev@lists.ozlabs.org, linux-nvdimm@lists.01.org
Cc: Santosh Sivaraj <santosh@fossix.org>,
	"Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
	Oliver O'Halloran <oohall@gmail.com>,
	Vaibhav Jain <vaibhav@linux.ibm.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Ira Weiny <ira.weiny@intel.com>
Subject: Re: [PATCH v2] powerpc/papr_scm: Fix warning triggered by perf_stats_show()
Date: Tue, 15 Sep 2020 21:30:08 +1000	[thread overview]
Message-ID: <87imcfp9a7.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <20200912081451.66225-1-vaibhav@linux.ibm.com>

Vaibhav Jain <vaibhav@linux.ibm.com> writes:
> A warning is reported by the kernel in case perf_stats_show() returns
> an error code. The warning is of the form below:
>
>  papr_scm ibm,persistent-memory:ibm,pmemory@44100001:
>  	  Failed to query performance stats, Err:-10
>  dev_attr_show: perf_stats_show+0x0/0x1c0 [papr_scm] returned bad count
>  fill_read_buffer: dev_attr_show+0x0/0xb0 returned bad count
>
> On investigation it looks like that the compiler is silently truncating the
> return value of drc_pmem_query_stats() from 'long' to 'int', since the
> variable used to store the return code 'rc' is an 'int'. This
> truncated value is then returned back as a 'ssize_t' back from
> perf_stats_show() to 'dev_attr_show()' which thinks of it as a large
> unsigned number and triggers this warning..
>
> To fix this we update the type of variable 'rc' from 'int' to
> 'ssize_t' that prevents the compiler from truncating the return value
> of drc_pmem_query_stats() and returning correct signed value back from
> perf_stats_show().
>
> Fixes: 2d02bf835e573 ('powerpc/papr_scm: Fetch nvdimm performance
>        stats from PHYP')

Please don't word wrap the Fixes tag it breaks b4.

I've fixed it up this time.

cheers

  parent reply	other threads:[~2020-09-15 11:30 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-12  8:14 [PATCH v2] powerpc/papr_scm: Fix warning triggered by perf_stats_show() Vaibhav Jain
2020-09-12  8:14 ` Vaibhav Jain
2020-09-14 16:56 ` Ira Weiny
2020-09-14 16:56   ` Ira Weiny
2020-09-15 11:30 ` Michael Ellerman [this message]
2020-09-15 11:30   ` Michael Ellerman
2020-09-15 16:03   ` Vaibhav Jain
2020-09-15 16:03     ` Vaibhav Jain
2020-09-17 11:27 ` Michael Ellerman
2020-09-17 11:27   ` Michael Ellerman

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=87imcfp9a7.fsf@mpe.ellerman.id.au \
    --to=mpe@ellerman.id.au \
    --cc=aneesh.kumar@linux.ibm.com \
    --cc=linux-nvdimm@lists.01.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=vaibhav@linux.ibm.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.