pci: endpoint: Replace mdelay with usleep_range in pci_epf_test_write

Message ID 1523365446-31563-1-git-send-email-baijiaju1990@gmail.com
State Accepted
Delegated to: Lorenzo Pieralisi
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Series
  • pci: endpoint: Replace mdelay with usleep_range in pci_epf_test_write
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Commit Message

Jia-Ju Bai April 10, 2018, 1:04 p.m.
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(-)

Comments

Lorenzo Pieralisi May 4, 2018, 4:29 p.m. | #1
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.

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
>
Kishon Vijay Abraham I May 5, 2018, 10:03 a.m. | #2
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
>>
Lorenzo Pieralisi May 8, 2018, 10:53 a.m. | #3
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(-)

Applied to pci/endpoint for v4.18, 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
>
Lorenzo Pieralisi May 11, 2018, 2:18 p.m. | #4
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(-)

Applied to pci/endpoint for v4.18, 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
>

Patch

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);