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Subject[PATCH] irq_enter() / wait_on_irq(), synchronize_irq() race fix
 This patch fixes races between irq_enter() <-> wait_on_ira() and
irq_enter() <-> synchronize_irq().

1. Archs which use bitops or spinlock for global_irq_lock
- adds smp_mb() to [hard_]irq_enter()
- adds smp_mb() to synchronize_irq()
=> alpha, i386, ia64, mips, mips64, parisc, x86_64
=> ppc also has atomic_inc() in hard_irq_enter(), so
smp_mb__after_atomic_inc() is used instead.

2. Archs which use brlock for global_irq_lock
- adds smp_mb() to synchronize_irq()
=> ppc64, sparc, sparc64

3. Archs with no SMP support
- nothing needed
=> arm, cris, generic, m68k, sh, sh64

4. Archs which don't seem to need irq_enter() synchronization to
disable irqs on on other CPUs.
- I don't know. Adds smp_mb() to synchronize_irq()?
=> s390, s390x

Please comment on how it should be done on s390 and s390x and point
out if anything is wrong.

--
tejun
# This is a BitKeeper generated patch for the following project:
# Project Name: Linux kernel tree
# This patch format is intended for GNU patch command version 2.5 or higher.
# This patch includes the following deltas:
# ChangeSet 1.1098 -> 1.1100
# arch/mips64/kernel/irq.c 1.5 -> 1.6
# include/asm-ppc/hardirq.h 1.8 -> 1.9
# include/asm-x86_64/hardirq.h 1.1 -> 1.2
# arch/sparc/kernel/irq.c 1.12 -> 1.13
# arch/alpha/kernel/irq_smp.c 1.2 -> 1.3
# arch/i386/kernel/irq.c 1.7 -> 1.8
# arch/mips/kernel/irq.c 1.8 -> 1.9
# arch/x86_64/kernel/irq.c 1.2 -> 1.3
# include/asm-ia64/hardirq.h 1.4 -> 1.5
# include/asm-mips/hardirq.h 1.3 -> 1.4
# arch/ia64/kernel/irq.c 1.9 -> 1.10
# arch/sparc64/kernel/irq.c 1.13 -> 1.14
# include/asm-mips64/hardirq.h 1.2 -> 1.3
# include/asm-alpha/hardirq.h 1.3 -> 1.4
# include/asm-i386/hardirq.h 1.4 -> 1.5
# arch/ppc/kernel/irq.c 1.18 -> 1.19
# arch/parisc/kernel/irq_smp.c 1.1 -> 1.2
# arch/ppc64/kernel/irq.c 1.3 -> 1.4
# include/asm-parisc/hardirq.h 1.2 -> 1.3
#
# The following is the BitKeeper ChangeSet Log
# --------------------------------------------
# 03/08/26 tj@atj.dyndns.org 1.1099
# - irq_enter() / wait_on_irq(), synchronize_irq() race fix.
# --------------------------------------------
# 03/08/26 tj@atj.dyndns.org 1.1100
# - irq race fix applied to other architectures.
# --------------------------------------------
#
diff -Nru a/arch/alpha/kernel/irq_smp.c b/arch/alpha/kernel/irq_smp.c
--- a/arch/alpha/kernel/irq_smp.c Tue Aug 26 10:01:05 2003
+++ b/arch/alpha/kernel/irq_smp.c Tue Aug 26 10:01:05 2003
@@ -242,6 +242,7 @@
} while (global_count != local_count);
#else
/* Jay's version. */
+ smp_mb(); /* Sync with irq_enter() */
if (irqs_running()) {
cli();
sti();
diff -Nru a/arch/i386/kernel/irq.c b/arch/i386/kernel/irq.c
--- a/arch/i386/kernel/irq.c Tue Aug 26 10:01:05 2003
+++ b/arch/i386/kernel/irq.c Tue Aug 26 10:01:05 2003
@@ -307,6 +307,7 @@
*/
void synchronize_irq(void)
{
+ smp_mb(); /* Sync with irq_enter() */
if (irqs_running()) {
/* Stupid approach */
cli();
diff -Nru a/arch/ia64/kernel/irq.c b/arch/ia64/kernel/irq.c
--- a/arch/ia64/kernel/irq.c Tue Aug 26 10:01:05 2003
+++ b/arch/ia64/kernel/irq.c Tue Aug 26 10:01:05 2003
@@ -344,6 +344,7 @@
*/
void synchronize_irq(void)
{
+ smp_mb(); /* Sync with irq_enter() */
if (irqs_running()) {
/* Stupid approach */
cli();
diff -Nru a/arch/mips/kernel/irq.c b/arch/mips/kernel/irq.c
--- a/arch/mips/kernel/irq.c Tue Aug 26 10:01:05 2003
+++ b/arch/mips/kernel/irq.c Tue Aug 26 10:01:05 2003
@@ -171,6 +171,7 @@
*/
void synchronize_irq(void)
{
+ smp_mb(); /* Sync with irq_enter() */
if (irqs_running()) {
/* Stupid approach */
cli();
diff -Nru a/arch/mips64/kernel/irq.c b/arch/mips64/kernel/irq.c
--- a/arch/mips64/kernel/irq.c Tue Aug 26 10:01:05 2003
+++ b/arch/mips64/kernel/irq.c Tue Aug 26 10:01:05 2003
@@ -171,6 +171,7 @@
*/
void synchronize_irq(void)
{
+ smp_mb(); /* Sync with irq_enter() */
if (irqs_running()) {
/* Stupid approach */
cli();
diff -Nru a/arch/parisc/kernel/irq_smp.c b/arch/parisc/kernel/irq_smp.c
--- a/arch/parisc/kernel/irq_smp.c Tue Aug 26 10:01:05 2003
+++ b/arch/parisc/kernel/irq_smp.c Tue Aug 26 10:01:05 2003
@@ -225,6 +225,7 @@
synchronize_irq(void)
{
/* Jay's version. */
+ smp_mb(); /* Sync with irq_enter() */
if (irqs_running()) {
cli();
sti();
diff -Nru a/arch/ppc/kernel/irq.c b/arch/ppc/kernel/irq.c
--- a/arch/ppc/kernel/irq.c Tue Aug 26 10:01:05 2003
+++ b/arch/ppc/kernel/irq.c Tue Aug 26 10:01:05 2003
@@ -675,6 +675,7 @@
*/
void synchronize_irq(void)
{
+ smp_mb(); /* Sync with irq_enter() */
if (atomic_read(&global_irq_count)) {
/* Stupid approach */
cli();
diff -Nru a/arch/ppc64/kernel/irq.c b/arch/ppc64/kernel/irq.c
--- a/arch/ppc64/kernel/irq.c Tue Aug 26 10:01:05 2003
+++ b/arch/ppc64/kernel/irq.c Tue Aug 26 10:01:05 2003
@@ -666,6 +666,7 @@

void synchronize_irq(void)
{
+ smp_mb(); /* Sync with irq_enter() */
if (irqs_running()) {
cli();
sti();
diff -Nru a/arch/sparc/kernel/irq.c b/arch/sparc/kernel/irq.c
--- a/arch/sparc/kernel/irq.c Tue Aug 26 10:01:05 2003
+++ b/arch/sparc/kernel/irq.c Tue Aug 26 10:01:05 2003
@@ -243,6 +243,7 @@
*/
void synchronize_irq(void)
{
+ smp_mb(); /* Sync with irq_enter() */
if (irqs_running()) {
cli();
sti();
diff -Nru a/arch/sparc64/kernel/irq.c b/arch/sparc64/kernel/irq.c
--- a/arch/sparc64/kernel/irq.c Tue Aug 26 10:01:05 2003
+++ b/arch/sparc64/kernel/irq.c Tue Aug 26 10:01:05 2003
@@ -592,6 +592,7 @@

void synchronize_irq(void)
{
+ smp_mb(); /* Sync with irq_enter() */
if (irqs_running()) {
cli();
sti();
diff -Nru a/arch/x86_64/kernel/irq.c b/arch/x86_64/kernel/irq.c
--- a/arch/x86_64/kernel/irq.c Tue Aug 26 10:01:05 2003
+++ b/arch/x86_64/kernel/irq.c Tue Aug 26 10:01:05 2003
@@ -333,6 +333,7 @@
*/
void synchronize_irq(void)
{
+ smp_mb(); /* Sync with irq_enter() */
if (irqs_running()) {
/* Stupid approach */
cli();
diff -Nru a/include/asm-alpha/hardirq.h b/include/asm-alpha/hardirq.h
--- a/include/asm-alpha/hardirq.h Tue Aug 26 10:01:05 2003
+++ b/include/asm-alpha/hardirq.h Tue Aug 26 10:01:05 2003
@@ -75,6 +75,8 @@
{
++local_irq_count(cpu);

+ smp_mb(); /* Sync with wait_on_irq() and synchronize_irq() */
+
while (spin_is_locked(&global_irq_lock))
barrier();
}
diff -Nru a/include/asm-i386/hardirq.h b/include/asm-i386/hardirq.h
--- a/include/asm-i386/hardirq.h Tue Aug 26 10:01:05 2003
+++ b/include/asm-i386/hardirq.h Tue Aug 26 10:01:05 2003
@@ -67,6 +67,8 @@
{
++local_irq_count(cpu);

+ smp_mb(); /* Sync with wait_on_irq() and synchronize_irq() */
+
while (test_bit(0,&global_irq_lock)) {
cpu_relax();
}
diff -Nru a/include/asm-ia64/hardirq.h b/include/asm-ia64/hardirq.h
--- a/include/asm-ia64/hardirq.h Tue Aug 26 10:01:05 2003
+++ b/include/asm-ia64/hardirq.h Tue Aug 26 10:01:05 2003
@@ -80,6 +80,8 @@
{
really_local_irq_count()++;

+ smp_mb(); /* Sync with wait_on_irq() and synchronize_irq() */
+
while (test_bit(0,&global_irq_lock)) {
/* nothing */;
}
diff -Nru a/include/asm-mips/hardirq.h b/include/asm-mips/hardirq.h
--- a/include/asm-mips/hardirq.h Tue Aug 26 10:01:05 2003
+++ b/include/asm-mips/hardirq.h Tue Aug 26 10:01:05 2003
@@ -82,6 +82,8 @@
{
++local_irq_count(cpu);

+ smp_mb(); /* Sync with wait_on_irq() and synchronize_irq() */
+
while (spin_is_locked(&global_irq_lock))
barrier();
}
diff -Nru a/include/asm-mips64/hardirq.h b/include/asm-mips64/hardirq.h
--- a/include/asm-mips64/hardirq.h Tue Aug 26 10:01:05 2003
+++ b/include/asm-mips64/hardirq.h Tue Aug 26 10:01:05 2003
@@ -81,6 +81,8 @@
{
++local_irq_count(cpu);

+ smp_mb(); /* Sync with wait_on_irq() and synchronize_irq() */
+
while (spin_is_locked(&global_irq_lock))
barrier();
}
diff -Nru a/include/asm-parisc/hardirq.h b/include/asm-parisc/hardirq.h
--- a/include/asm-parisc/hardirq.h Tue Aug 26 10:01:05 2003
+++ b/include/asm-parisc/hardirq.h Tue Aug 26 10:01:05 2003
@@ -82,6 +82,8 @@
{
++local_irq_count(cpu);

+ smp_mb(); /* Sync with wait_on_irq() and synchronize_irq() */
+
while (spin_is_locked(&global_irq_lock))
barrier();
}
diff -Nru a/include/asm-ppc/hardirq.h b/include/asm-ppc/hardirq.h
--- a/include/asm-ppc/hardirq.h Tue Aug 26 10:01:05 2003
+++ b/include/asm-ppc/hardirq.h Tue Aug 26 10:01:05 2003
@@ -69,6 +69,7 @@

++local_irq_count(cpu);
atomic_inc(&global_irq_count);
+ smp_mb__after_atomic_inc(); /* Sync with wait_on_irq() and synchronize_irq() */
while (test_bit(0,&global_irq_lock)) {
if (cpu == global_irq_holder) {
printk("uh oh, interrupt while we hold global irq lock! (CPU %d)\n", cpu);
diff -Nru a/include/asm-x86_64/hardirq.h b/include/asm-x86_64/hardirq.h
--- a/include/asm-x86_64/hardirq.h Tue Aug 26 10:01:05 2003
+++ b/include/asm-x86_64/hardirq.h Tue Aug 26 10:01:05 2003
@@ -67,6 +67,8 @@
{
++local_irq_count(cpu);

+ smp_mb(); /* Sync with wait_on_irq() and synchronize_irq() */
+
while (test_bit(0,&global_irq_lock)) {
cpu_relax();
}
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