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authorAnton Blanchard <anton@samba.org>2010-10-21 00:52:12 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2011-02-07 13:06:08 +1100
commit57cdfdf829a850a317425ed93c6a576c9ee6329c (patch)
tree80e1e9e5f742e2a67ed4e43e6cc2e2823f27e72d /arch/powerpc
parent429f4d8d20b91e4a6c239f951c06a56a6ac22957 (diff)
downloadlinux-2.6.38-lt-ux500-57cdfdf829a850a317425ed93c6a576c9ee6329c.tar.gz
powerpc: Fix hcall tracepoint recursion
Spinlocks on shared processor partitions use H_YIELD to notify the hypervisor we are waiting on another virtual CPU. Unfortunately this means the hcall tracepoints can recurse. The patch below adds a percpu depth and checks it on both the entry and exit hcall tracepoints. Signed-off-by: Anton Blanchard <anton@samba.org> Acked-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> CC: stable@kernel.org
Diffstat (limited to 'arch/powerpc')
-rw-r--r--arch/powerpc/platforms/pseries/lpar.c37
1 files changed, 37 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index 5d3ea9f60dd..ca5d5898d32 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -713,6 +713,13 @@ EXPORT_SYMBOL(arch_free_page);
/* NB: reg/unreg are called while guarded with the tracepoints_mutex */
extern long hcall_tracepoint_refcount;
+/*
+ * Since the tracing code might execute hcalls we need to guard against
+ * recursion. One example of this are spinlocks calling H_YIELD on
+ * shared processor partitions.
+ */
+static DEFINE_PER_CPU(unsigned int, hcall_trace_depth);
+
void hcall_tracepoint_regfunc(void)
{
hcall_tracepoint_refcount++;
@@ -725,12 +732,42 @@ void hcall_tracepoint_unregfunc(void)
void __trace_hcall_entry(unsigned long opcode, unsigned long *args)
{
+ unsigned long flags;
+ unsigned int *depth;
+
+ local_irq_save(flags);
+
+ depth = &__get_cpu_var(hcall_trace_depth);
+
+ if (*depth)
+ goto out;
+
+ (*depth)++;
trace_hcall_entry(opcode, args);
+ (*depth)--;
+
+out:
+ local_irq_restore(flags);
}
void __trace_hcall_exit(long opcode, unsigned long retval,
unsigned long *retbuf)
{
+ unsigned long flags;
+ unsigned int *depth;
+
+ local_irq_save(flags);
+
+ depth = &__get_cpu_var(hcall_trace_depth);
+
+ if (*depth)
+ goto out;
+
+ (*depth)++;
trace_hcall_exit(opcode, retval, retbuf);
+ (*depth)--;
+
+out:
+ local_irq_restore(flags);
}
#endif