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

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>

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 65c7857a90ddfc6ff084c6817baba045ced0ad71..d5ccf42267e47d1edd0876a48d1cc9aafa760e84 100644 (file)
--- 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 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