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* [PATCH] pci: endpoint: Replace mdelay with usleep_range in pci_epf_test_write
@ 2018-04-10 13:04 Jia-Ju Bai
  2018-05-04 16:29 ` Lorenzo Pieralisi
                   ` (2 more replies)
  0 siblings, 3 replies; 5+ messages in thread
From: Jia-Ju Bai @ 2018-04-10 13:04 UTC (permalink / raw)
  To: kishon, bhelgaas, nsekhar, john, shawn.lin
  Cc: linux-pci, linux-kernel, Jia-Ju Bai

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(-)

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

^ permalink raw reply	[flat|nested] 5+ messages in thread

end of thread, other threads:[~2018-05-11 14:18 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-04-10 13:04 [PATCH] pci: endpoint: Replace mdelay with usleep_range in pci_epf_test_write Jia-Ju Bai
2018-05-04 16:29 ` Lorenzo Pieralisi
2018-05-05 10:03   ` Kishon Vijay Abraham I
2018-05-08 10:53 ` Lorenzo Pieralisi
2018-05-11 14:18 ` Lorenzo Pieralisi

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