vserver 1.9.3

[linux-2.6.git] / arch / x86_64 / kernel / smp.c

diff --git a/arch/x86_64/kernel/smp.c b/arch/x86_64/kernel/smp.c
index 409460e..269ef09 100644 (file)
--- a/arch/x86_64/kernel/smp.c
+++ b/arch/x86_64/kernel/smp.c
@@ -382,30 +382,14 @@ static struct call_data_struct * call_data;
  * this function sends a 'generic call function' IPI to all other CPUs
  * in the system.
  */
-
-int smp_call_function (void (*func) (void *info), void *info, int nonatomic,
-                       int wait)
-/*
- * [SUMMARY] Run a function on all other CPUs.
- * <func> The function to run. This must be fast and non-blocking.
- * <info> An arbitrary pointer to pass to the function.
- * <nonatomic> currently unused.
- * <wait> If true, wait (atomically) until function has completed on other CPUs.
- * [RETURNS] 0 on success, else a negative status code. Does not return until
- * remote CPUs are nearly ready to execute <<func>> or are or have executed.
- *
- * You must not call this function with disabled interrupts or from a
- * hardware interrupt handler or from a bottom half handler.
- */
+static void __smp_call_function (void (*func) (void *info), void *info,
+                               int nonatomic, int wait)
 {
        struct call_data_struct data;
        int cpus = num_online_cpus()-1;
 
        if (!cpus)
-               return 0;
-
-       /* Can deadlock when called with interrupts disabled */
-       WARN_ON(irqs_disabled());
+               return;
 
        data.func = func;
        data.info = info;
@@ -414,7 +398,6 @@ int smp_call_function (void (*func) (void *info), void *info, int nonatomic,
        if (wait)
                atomic_set(&data.finished, 0);
 
-       spin_lock(&call_lock);
        call_data = &data;
        wmb();
        /* Send a message to all other CPUs and wait for them to respond */
@@ -427,8 +410,29 @@ int smp_call_function (void (*func) (void *info), void *info, int nonatomic,
        if (wait)
                while (atomic_read(&data.finished) != cpus)
                        barrier();
-       spin_unlock(&call_lock);
+}
 
+/*
+ * smp_call_function - run a function on all other CPUs.
+ * @func: The function to run. This must be fast and non-blocking.
+ * @info: An arbitrary pointer to pass to the function.
+ * @nonatomic: currently unused.
+ * @wait: If true, wait (atomically) until function has completed on other
+ *        CPUs.
+ *
+ * Returns 0 on success, else a negative status code. Does not return until
+ * remote CPUs are nearly ready to execute func or are or have executed.
+ *
+ * You must not call this function with disabled interrupts or from a
+ * hardware interrupt handler or from a bottom half handler.
+ * Actually there are a few legal cases, like panic.
+ */
+int smp_call_function (void (*func) (void *info), void *info, int nonatomic,
+                       int wait)
+{
+       spin_lock(&call_lock);
+       __smp_call_function(func,info,nonatomic,wait);
+       spin_unlock(&call_lock);
        return 0;
 }
 
@@ -452,7 +456,16 @@ static void smp_really_stop_cpu(void *dummy)
 
 void smp_send_stop(void)
 {
-       smp_call_function(smp_really_stop_cpu, NULL, 1, 0);
+       int nolock = 0;
+       /* Don't deadlock on the call lock in panic */
+       if (!spin_trylock(&call_lock)) {
+               udelay(100);
+               /* ignore locking because we have paniced anyways */
+               nolock = 1;
+       }
+       __smp_call_function(smp_really_stop_cpu, NULL, 1, 0);
+       if (!nolock)
+               spin_unlock(&call_lock);
        smp_stop_cpu();
 }