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Subject[PATCH 1/2] pci: host: pci-hyperv: Replace GFP_ATOMIC with GFP_KERNEL in hv_pci_onchannelcallback
Date
hv_pci_onchannelcallback() is not called in atomic context.

The call chain ending up at hv_pci_onchannelcallback() is:
[1] hv_pci_onchannelcallback() <- hv_pci_probe()
hv_pci_probe() is only set as ".probe" in hv_driver
structure "hv_pci_drv".

Despite never getting called from atomic context,
hv_pci_onchannelcallback() calls kmalloc with GFP_ATOMIC,
which waits busily for allocation.
GFP_ATOMIC is not necessary and can be replaced with GFP_KERNEL
to avoid busy waiting.

This is found by a static analysis tool named DCNS written by myself.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
---
drivers/pci/host/pci-hyperv.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
index 0fe3ea1..c5c8a99 100644
--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -1887,7 +1887,7 @@ static void hv_pci_onchannelcallback(void *context)
struct pci_dev_incoming *dev_message;
struct hv_pci_dev *hpdev;

- buffer = kmalloc(bufferlen, GFP_ATOMIC);
+ buffer = kmalloc(bufferlen, GFP_KERNEL);
if (!buffer)
return;

@@ -1899,7 +1899,7 @@ static void hv_pci_onchannelcallback(void *context)
kfree(buffer);
/* Handle large packet */
bufferlen = bytes_recvd;
- buffer = kmalloc(bytes_recvd, GFP_ATOMIC);
+ buffer = kmalloc(bytes_recvd, GFP_KERNEL);
if (!buffer)
return;
continue;
--
1.9.1
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