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authorEric W. Biederman <ebiederm@xmission.com>2005-07-29 14:03:29 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2005-07-29 15:01:13 -0700
commit3d483f47579461a4715db33c68ef8752e5a97a2d (patch)
tree6a4c9022074426d3551ff1b47c95f2bfe3f41828 /arch/x86_64/kernel/smp.c
parent94d2ac66c12397e2ca7988dbf59f24a966d275cb (diff)
[PATCH] Fix sync_tsc hang
sync_tsc was using smp_call_function to ask the boot processor to report it's tsc value. smp_call_function performs an IPI_send_allbutself which is a broadcast ipi. There is a window during processor startup during which the target cpu has started and before it has initialized it's interrupt vectors so it can properly process an interrupt. Receveing an interrupt during that window will triple fault the cpu and do other nasty things. Why cli does not protect us from that is beyond me. The simple fix is to match ia64 and provide a smp_call_function_single. Which avoids the broadcast and is more efficient. This certainly fixes the problem of getting stuck on boot which was very easy to trigger on my SMP Hyperthreaded Xeon, and I think it fixes it for the right reasons. Minor changes by AK Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/x86_64/kernel/smp.c')
-rw-r--r--arch/x86_64/kernel/smp.c63
1 files changed, 63 insertions, 0 deletions
diff --git a/arch/x86_64/kernel/smp.c b/arch/x86_64/kernel/smp.c
index 6ee74db5230..e5958220d6b 100644
--- a/arch/x86_64/kernel/smp.c
+++ b/arch/x86_64/kernel/smp.c
@@ -293,6 +293,69 @@ void unlock_ipi_call_lock(void)
}
/*
+ * this function sends a 'generic call function' IPI to one other CPU
+ * in the system.
+ */
+static void __smp_call_function_single (int cpu, void (*func) (void *info), void *info,
+ int nonatomic, int wait)
+{
+ struct call_data_struct data;
+ int cpus = 1;
+
+ data.func = func;
+ data.info = info;
+ atomic_set(&data.started, 0);
+ data.wait = wait;
+ if (wait)
+ atomic_set(&data.finished, 0);
+
+ call_data = &data;
+ wmb();
+ /* Send a message to all other CPUs and wait for them to respond */
+ send_IPI_mask(cpumask_of_cpu(cpu), CALL_FUNCTION_VECTOR);
+
+ /* Wait for response */
+ while (atomic_read(&data.started) != cpus)
+ cpu_relax();
+
+ if (!wait)
+ return;
+
+ while (atomic_read(&data.finished) != cpus)
+ cpu_relax();
+}
+
+/*
+ * smp_call_function_single - Run a function on another CPU
+ * @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 until function has completed on other CPUs.
+ *
+ * Retrurns 0 on success, else a negative status code.
+ *
+ * Does not return until the remote CPU is nearly ready to execute <func>
+ * or is or has executed.
+ */
+
+int smp_call_function_single (int cpu, void (*func) (void *info), void *info,
+ int nonatomic, int wait)
+{
+ /* prevent preemption and reschedule on another processor */
+ int me = get_cpu();
+ if (cpu == me) {
+ WARN_ON(1);
+ put_cpu();
+ return -EBUSY;
+ }
+ spin_lock_bh(&call_lock);
+ __smp_call_function_single(cpu, func, info, nonatomic, wait);
+ spin_unlock_bh(&call_lock);
+ put_cpu();
+ return 0;
+}
+
+/*
* this function sends a 'generic call function' IPI to all other CPUs
* in the system.
*/