diff options
author | Anton Blanchard <anton@samba.org> | 2010-10-21 00:52:12 (GMT) |
---|---|---|
committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2011-02-07 02:06:08 (GMT) |
commit | 57cdfdf829a850a317425ed93c6a576c9ee6329c (patch) | |
tree | 80e1e9e5f742e2a67ed4e43e6cc2e2823f27e72d /arch/powerpc | |
parent | 429f4d8d20b91e4a6c239f951c06a56a6ac22957 (diff) | |
download | linux-fsl-qoriq-57cdfdf829a850a317425ed93c6a576c9ee6329c.tar.xz |
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.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 5d3ea9f..ca5d589 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 |