LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Kishon Vijay Abraham I <kishon@ti.com>
To: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Jia-Ju Bai <baijiaju1990@gmail.com>
Cc: <bhelgaas@google.com>, <nsekhar@ti.com>, <john@metanate.com>,
	<shawn.lin@rock-chips.com>, <linux-pci@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] pci: endpoint: Replace mdelay with usleep_range in pci_epf_test_write
Date: Sat, 5 May 2018 15:33:11 +0530	[thread overview]
Message-ID: <de84ea55-5949-dec5-ad8b-5845b99285c0@ti.com> (raw)
In-Reply-To: <20180504162932.GA16953@e107981-ln.cambridge.arm.com>



On Friday 04 May 2018 09:59 PM, Lorenzo Pieralisi wrote:
> On Tue, Apr 10, 2018 at 09:04:06PM +0800, Jia-Ju Bai wrote:
>> pci_epf_test_write() is never called in atomic context.
>>
>> The call chain ending up at pci_epf_test_write() is:
>> [1] pci_epf_test_write() <- pci_epf_test_cmd_handler()
>>
>> pci_epf_test_cmd_handler() is set as a parameter of INIT_DELAYED_WORK() 
>> in pci_epf_test_probe().
>> This function is not called in atomic context.
>>
>> Despite never getting called from atomic context, pci_epf_test_write()
>> calls mdelay() to busily wait.
>> This is not necessary and can be replaced with usleep_range() to
>> avoid busy waiting.
>>
>> This is found by a static analysis tool named DCNS written by myself.
>> And I also manually check it.
>>
>> Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
>> ---
>>  drivers/pci/endpoint/functions/pci-epf-test.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> I'd request Kishon's ACK on this.

sorry, missed this before.

Acked-by: Kishon Vijay Abraham I <kishon@ti.com>
> 
> Thanks,
> Lorenzo
> 
>> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
>> index f9308c2..2f0642e 100644
>> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
>> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
>> @@ -237,7 +237,7 @@ static int pci_epf_test_write(struct pci_epf_test *epf_test)
>>  	 * wait 1ms inorder for the write to complete. Without this delay L3
>>  	 * error in observed in the host system.
>>  	 */
>> -	mdelay(1);
>> +	usleep_range(1000, 2000);
>>  
>>  	kfree(buf);
>>  
>> -- 
>> 1.9.1
>>

  reply	other threads:[~2018-05-05 10:03 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-10 13:04 Jia-Ju Bai
2018-05-04 16:29 ` Lorenzo Pieralisi
2018-05-05 10:03   ` Kishon Vijay Abraham I [this message]
2018-05-08 10:53 ` Lorenzo Pieralisi
2018-05-11 14:18 ` Lorenzo Pieralisi

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=de84ea55-5949-dec5-ad8b-5845b99285c0@ti.com \
    --to=kishon@ti.com \
    --cc=baijiaju1990@gmail.com \
    --cc=bhelgaas@google.com \
    --cc=john@metanate.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pci@vger.kernel.org \
    --cc=lorenzo.pieralisi@arm.com \
    --cc=nsekhar@ti.com \
    --cc=shawn.lin@rock-chips.com \
    --subject='Re: [PATCH] pci: endpoint: Replace mdelay with usleep_range in pci_epf_test_write' \
    /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

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).