linux-kernel - [PATCH 2/2] block: DAC960: Replace GFP_ATOMIC with GFP_KERNEL in DAC960

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Date:   Fri, 26 Jan 2018 18:25:50 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     keescook@...omium.org, axboe@...nel.dk, arnd@...db.de
Cc:     linux-kernel@...r.kernel.org, Jia-Ju Bai <baijiaju1990@...il.com>
Subject: [PATCH 2/2] block: DAC960: Replace GFP_ATOMIC with GFP_KERNEL in DAC960_CreateAuxiliaryStructures

After checking all possible call chains to 
DAC960_CreateAuxiliaryStructures(),
my tool finds that this function is never called in atomic context,
namely never in an interrupt handler or holding a spinlock.
And DAC960_CreateAuxiliaryStructures() calls 
pci_pool_create() and pci_pool_destroy() that can sleep,
so it indicates that DAC960_CreateAuxiliaryStructures() can call 
functions which may sleep.
Thus GFP_ATOMIC is not necessary, and it can be replaced with GFP_KERNEL.

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

Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
---
 drivers/block/DAC960.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/block/DAC960.c b/drivers/block/DAC960.c
index 442e777..39fc016 100644
--- a/drivers/block/DAC960.c
+++ b/drivers/block/DAC960.c
@@ -323,7 +323,7 @@ static bool DAC960_CreateAuxiliaryStructures(DAC960_Controller_T *Controller)
 		CommandsRemaining = CommandAllocationGroupSize;
 	  CommandGroupByteCount =
 		CommandsRemaining * CommandAllocationLength;
-	  AllocationPointer = kzalloc(CommandGroupByteCount, GFP_ATOMIC);
+	  AllocationPointer = kzalloc(CommandGroupByteCount, GFP_KERNEL);
 	  if (AllocationPointer == NULL)
 		return DAC960_Failure(Controller,
 					"AUXILIARY STRUCTURE CREATION");
@@ -335,13 +335,13 @@ static bool DAC960_CreateAuxiliaryStructures(DAC960_Controller_T *Controller)
       Command->Next = Controller->FreeCommands;
       Controller->FreeCommands = Command;
       Controller->Commands[CommandIdentifier-1] = Command;
-      ScatterGatherCPU = pci_pool_alloc(ScatterGatherPool, GFP_ATOMIC,
+      ScatterGatherCPU = pci_pool_alloc(ScatterGatherPool, GFP_KERNEL,
 							&ScatterGatherDMA);
       if (ScatterGatherCPU == NULL)
 	  return DAC960_Failure(Controller, "AUXILIARY STRUCTURE CREATION");
 
       if (RequestSensePool != NULL) {
-  	  RequestSenseCPU = pci_pool_alloc(RequestSensePool, GFP_ATOMIC,
+  	  RequestSenseCPU = pci_pool_alloc(RequestSensePool, GFP_KERNEL,
 						&RequestSenseDMA);
   	  if (RequestSenseCPU == NULL) {
                 pci_pool_free(ScatterGatherPool, ScatterGatherCPU,
-- 
1.7.9.5