linux-kernel - [PATCH 4/4] xen: xen-pciback: Replace GFP_ATOMIC with GFP_KERNEL in xen_pcibk_config_quirks

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Date:   Mon,  9 Apr 2018 23:04:25 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     boris.ostrovsky@...cle.com, jgross@...e.com,
        gregkh@...uxfoundation.org
Cc:     xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org,
        Jia-Ju Bai <baijiaju1990@...il.com>
Subject: [PATCH 4/4] xen: xen-pciback: Replace GFP_ATOMIC with GFP_KERNEL in xen_pcibk_config_quirks_init

xen_pcibk_config_quirks_init() is never called in atomic context.

The call chains ending up at xen_pcibk_config_quirks_init() are:
[1] xen_pcibk_config_quirks_init() <- xen_pcibk_config_init_dev() <- 
	pcistub_init_device() <- pcistub_seize() <- pcistub_probe()
[2] xen_pcibk_config_quirks_init() <- xen_pcibk_config_init_dev() <- 
	pcistub_init_device() <- pcistub_init_devices_late() <- 
	xen_pcibk_init()
pcistub_probe() is only set as ".probe" in struct pci_driver.
xen_pcibk_init() is is only set as a parameter of module_init().
These functions are not called in atomic context.

Despite never getting called from atomic context,
xen_pcibk_config_quirks_init() calls kzalloc() with GFP_ATOMIC,
which does not sleep for allocation.
GFP_ATOMIC is not necessary and can be replaced with GFP_KERNEL,
which can sleep and improve the possibility of sucessful allocation.

Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
---
 drivers/xen/xen-pciback/conf_space_quirks.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/xen/xen-pciback/conf_space_quirks.c b/drivers/xen/xen-pciback/conf_space_quirks.c
index 7476791..e3df3f9 100644
--- a/drivers/xen/xen-pciback/conf_space_quirks.c
+++ b/drivers/xen/xen-pciback/conf_space_quirks.c
@@ -94,7 +94,7 @@ int xen_pcibk_config_quirks_init(struct pci_dev *dev)
 	struct xen_pcibk_config_quirk *quirk;
 	int ret = 0;
 
-	quirk = kzalloc(sizeof(*quirk), GFP_ATOMIC);
+	quirk = kzalloc(sizeof(*quirk), GFP_KERNEL);
 	if (!quirk) {
 		ret = -ENOMEM;
 		goto out;
-- 
1.9.1