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Message-ID: <47D807BA.7020102@hp.com>
Date: Wed, 12 Mar 2008 12:41:30 -0400
From: "Alan D. Brunelle" <Alan.Brunelle@...com>
To: Jens Axboe <jens.axboe@...cle.com>
Cc: linux-kernel@...r.kernel.org, npiggin@...e.de, dgc@....com
Subject: Re: [PATCH 0/7] IO CPU affinity testing series
Subject: [PATCH] Fixed race: using potentially invalid pointer
When data->flags & CSD_FLAG_ALLOC is true, the data could be freed by the other processor before we check for CSD_FLAG_WAIT.
Also: removed old comment, doesn't quite fit anymore.
This is applied against Jens' git tree w/ the ia64 additional commit.
Signed-off-by: Alan D. Brunelle <alan.brunelle@...com>
---
arch/ia64/kernel/smp.c | 5 ++---
arch/x86/kernel/smp_32.c | 5 ++---
arch/x86/kernel/smp_64.c | 5 ++---
3 files changed, 6 insertions(+), 9 deletions(-)
diff --git a/arch/ia64/kernel/smp.c b/arch/ia64/kernel/smp.c
index 521bc52..ad153e2 100644
--- a/arch/ia64/kernel/smp.c
+++ b/arch/ia64/kernel/smp.c
@@ -407,8 +407,7 @@ void __smp_call_function_single(int cpu, struct call_single_data *data)
{
struct call_single_queue *dst;
unsigned long flags;
- /* prevent preemption and reschedule on another processor */
- int ipi;
+ int ipi, wait_done = data->flags & CSD_FLAG_WAIT;
/* Can deadlock when called with interrupts disabled */
WARN_ON((data->flags & CSD_FLAG_WAIT) && irqs_disabled());
@@ -424,7 +423,7 @@ void __smp_call_function_single(int cpu, struct call_single_data *data)
if (ipi)
send_IPI_single(cpu, IPI_CALL_FUNC_SINGLE);
- if (data->flags & CSD_FLAG_WAIT) {
+ if (wait_done) {
/* Wait for response */
while (data->flags)
cpu_relax();
diff --git a/arch/x86/kernel/smp_32.c b/arch/x86/kernel/smp_32.c
index dcbb89c..8239814 100644
--- a/arch/x86/kernel/smp_32.c
+++ b/arch/x86/kernel/smp_32.c
@@ -638,8 +638,7 @@ void __smp_call_function_single(int cpu, struct call_single_data *data)
cpumask_t mask = cpumask_of_cpu(cpu);
struct call_single_queue *dst;
unsigned long flags;
- /* prevent preemption and reschedule on another processor */
- int ipi;
+ int ipi, wait_done = data->flags & CSD_FLAG_WAIT;
/* Can deadlock when called with interrupts disabled */
WARN_ON((data->flags & CSD_FLAG_WAIT) && irqs_disabled());
@@ -655,7 +654,7 @@ void __smp_call_function_single(int cpu, struct call_single_data *data)
if (ipi)
send_IPI_mask(mask, CALL_FUNCTION_SINGLE_VECTOR);
- if (data->flags & CSD_FLAG_WAIT) {
+ if (wait_done) {
/* Wait for response */
while (data->flags)
cpu_relax();
diff --git a/arch/x86/kernel/smp_64.c b/arch/x86/kernel/smp_64.c
index 7e4e300..c89a4f7 100644
--- a/arch/x86/kernel/smp_64.c
+++ b/arch/x86/kernel/smp_64.c
@@ -458,8 +458,7 @@ void __smp_call_function_single(int cpu, struct call_single_data *data)
cpumask_t mask = cpumask_of_cpu(cpu);
struct call_single_queue *dst;
unsigned long flags;
- /* prevent preemption and reschedule on another processor */
- int ipi;
+ int ipi, wait_done = data->flags & CSD_FLAG_WAIT;
/* Can deadlock when called with interrupts disabled */
WARN_ON((data->flags & CSD_FLAG_WAIT) && irqs_disabled());
@@ -475,7 +474,7 @@ void __smp_call_function_single(int cpu, struct call_single_data *data)
if (ipi)
send_IPI_mask(mask, CALL_FUNCTION_SINGLE_VECTOR);
- if (data->flags & CSD_FLAG_WAIT) {
+ if (wait_done) {
/* Wait for response */
while (data->flags)
cpu_relax();
--
1.5.2.5
--
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