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Subject[patch 35/71] x86: fix SMP alternatives: use mutex instead of spinlock, text_poke is sleepable
2.6.26-stable review patch.  If anyone has any objections, please let us
know.

------------------
From: Pekka Paalanen <pq@iki.fi>
commit 2f1dafe50cc4e58a239fd81bd47f87f32042a1ee upstream

text_poke is sleepable.
The original fix by Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>.

Signed-off-by: Pekka Paalanen <pq@iki.fi>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
arch/x86/kernel/alternative.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -1,6 +1,6 @@
#include <linux/module.h>
#include <linux/sched.h>
-#include <linux/spinlock.h>
+#include <linux/mutex.h>
#include <linux/list.h>
#include <linux/kprobes.h>
#include <linux/mm.h>
@@ -279,7 +279,7 @@ struct smp_alt_module {
struct list_head next;
};
static LIST_HEAD(smp_alt_modules);
-static DEFINE_SPINLOCK(smp_alt);
+static DEFINE_MUTEX(smp_alt);
static int smp_mode = 1; /* protected by smp_alt */

void alternatives_smp_module_add(struct module *mod, char *name,
@@ -312,12 +312,12 @@ void alternatives_smp_module_add(struct
__func__, smp->locks, smp->locks_end,
smp->text, smp->text_end, smp->name);

- spin_lock(&smp_alt);
+ mutex_lock(&smp_alt);
list_add_tail(&smp->next, &smp_alt_modules);
if (boot_cpu_has(X86_FEATURE_UP))
alternatives_smp_unlock(smp->locks, smp->locks_end,
smp->text, smp->text_end);
- spin_unlock(&smp_alt);
+ mutex_unlock(&smp_alt);
}

void alternatives_smp_module_del(struct module *mod)
@@ -327,17 +327,17 @@ void alternatives_smp_module_del(struct
if (smp_alt_once || noreplace_smp)
return;

- spin_lock(&smp_alt);
+ mutex_lock(&smp_alt);
list_for_each_entry(item, &smp_alt_modules, next) {
if (mod != item->mod)
continue;
list_del(&item->next);
- spin_unlock(&smp_alt);
+ mutex_unlock(&smp_alt);
DPRINTK("%s: %s\n", __func__, item->name);
kfree(item);
return;
}
- spin_unlock(&smp_alt);
+ mutex_unlock(&smp_alt);
}

void alternatives_smp_switch(int smp)
@@ -359,7 +359,7 @@ void alternatives_smp_switch(int smp)
return;
BUG_ON(!smp && (num_online_cpus() > 1));

- spin_lock(&smp_alt);
+ mutex_lock(&smp_alt);

/*
* Avoid unnecessary switches because it forces JIT based VMs to
@@ -383,7 +383,7 @@ void alternatives_smp_switch(int smp)
mod->text, mod->text_end);
}
smp_mode = smp;
- spin_unlock(&smp_alt);
+ mutex_unlock(&smp_alt);
}

#endif
--


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