diff options
author | Anton Blanchard <anton@samba.org> | 2010-10-21 00:52:12 +0000 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-02-17 14:47:20 -0800 |
commit | 3ca30e408a08f9b902d4d7d0422be498584cb966 (patch) | |
tree | 15c9ebd73658fb56f3bada294f603ce96b8241a0 /arch | |
parent | 1caf470a3c4ab570b38a6e7c339e06f18909ef98 (diff) |
powerpc: Fix hcall tracepoint recursion
commit 57cdfdf829a850a317425ed93c6a576c9ee6329c upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/powerpc/platforms/pseries/lpar.c | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c index cf79b46d8f88..568b503d68bd 100644 --- a/arch/powerpc/platforms/pseries/lpar.c +++ b/arch/powerpc/platforms/pseries/lpar.c @@ -680,6 +680,13 @@ 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++; @@ -692,12 +699,42 @@ 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 |