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authorLinus Torvalds <torvalds@linux-foundation.org>2009-01-31 15:55:05 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-31 15:55:05 -0800
commit1347e965f5bcfffe82e56d2903ea4f32babaff4e (patch)
tree51f75d125089a25feb12b9e2e1e5273a59836e32
parentac56b94f8049b4c246cd86257ae6c03c0ac75a13 (diff)
parentd7240b988017521ebf89edfadd42c0942f166850 (diff)
Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: generic-ipi: use per cpu data for single cpu ipi calls cpumask: convert lib/smp_processor_id to new cpumask ops signals, debug: fix BUG: using smp_processor_id() in preemptible code in print_fatal_signal()
-rw-r--r--kernel/signal.c2
-rw-r--r--kernel/smp.c36
-rw-r--r--lib/smp_processor_id.c2
3 files changed, 36 insertions, 4 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index e73759783dc..b6b36768b75 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -909,7 +909,9 @@ static void print_fatal_signal(struct pt_regs *regs, int signr)
}
#endif
printk("\n");
+ preempt_disable();
show_regs(regs);
+ preempt_enable();
}
static int __init setup_print_fatal_signals(char *str)
diff --git a/kernel/smp.c b/kernel/smp.c
index 5cfa0e5e3e8..bbedbb7efe3 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -18,6 +18,7 @@ __cacheline_aligned_in_smp DEFINE_SPINLOCK(call_function_lock);
enum {
CSD_FLAG_WAIT = 0x01,
CSD_FLAG_ALLOC = 0x02,
+ CSD_FLAG_LOCK = 0x04,
};
struct call_function_data {
@@ -186,6 +187,9 @@ void generic_smp_call_function_single_interrupt(void)
if (data_flags & CSD_FLAG_WAIT) {
smp_wmb();
data->flags &= ~CSD_FLAG_WAIT;
+ } else if (data_flags & CSD_FLAG_LOCK) {
+ smp_wmb();
+ data->flags &= ~CSD_FLAG_LOCK;
} else if (data_flags & CSD_FLAG_ALLOC)
kfree(data);
}
@@ -196,6 +200,8 @@ void generic_smp_call_function_single_interrupt(void)
}
}
+static DEFINE_PER_CPU(struct call_single_data, csd_data);
+
/*
* smp_call_function_single - Run a function on a specific CPU
* @func: The function to run. This must be fast and non-blocking.
@@ -224,14 +230,38 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
func(info);
local_irq_restore(flags);
} else if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
- struct call_single_data *data = NULL;
+ struct call_single_data *data;
if (!wait) {
+ /*
+ * We are calling a function on a single CPU
+ * and we are not going to wait for it to finish.
+ * We first try to allocate the data, but if we
+ * fail, we fall back to use a per cpu data to pass
+ * the information to that CPU. Since all callers
+ * of this code will use the same data, we must
+ * synchronize the callers to prevent a new caller
+ * from corrupting the data before the callee
+ * can access it.
+ *
+ * The CSD_FLAG_LOCK is used to let us know when
+ * the IPI handler is done with the data.
+ * The first caller will set it, and the callee
+ * will clear it. The next caller must wait for
+ * it to clear before we set it again. This
+ * will make sure the callee is done with the
+ * data before a new caller will use it.
+ */
data = kmalloc(sizeof(*data), GFP_ATOMIC);
if (data)
data->flags = CSD_FLAG_ALLOC;
- }
- if (!data) {
+ else {
+ data = &per_cpu(csd_data, me);
+ while (data->flags & CSD_FLAG_LOCK)
+ cpu_relax();
+ data->flags = CSD_FLAG_LOCK;
+ }
+ } else {
data = &d;
data->flags = CSD_FLAG_WAIT;
}
diff --git a/lib/smp_processor_id.c b/lib/smp_processor_id.c
index 0f8fc22ed10..4689cb073da 100644
--- a/lib/smp_processor_id.c
+++ b/lib/smp_processor_id.c
@@ -22,7 +22,7 @@ notrace unsigned int debug_smp_processor_id(void)
* Kernel threads bound to a single CPU can safely use
* smp_processor_id():
*/
- if (cpus_equal(current->cpus_allowed, cpumask_of_cpu(this_cpu)))
+ if (cpumask_equal(&current->cpus_allowed, cpumask_of(this_cpu)))
goto out;
/*