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Commit 2f1dafe5 authored by Pekka Paalanen's avatar Pekka Paalanen Committed by Thomas Gleixner
Browse files

x86: fix SMP alternatives: use mutex instead of spinlock, text_poke is sleepable 



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

Signed-off-by: default avatarPekka Paalanen <pq@iki.fi>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 107bad8b

arch/x86/kernel/alternative.c

+9 −9
Original line number Diff line number Diff line 
#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 module *mod, char *name, 
		__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 module *mod) 
	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