| Message ID | 20081117191059.610706327@goodmis.org (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c index 918a5d2..81e338c 100644 --- a/arch/powerpc/kernel/ftrace.c +++ b/arch/powerpc/kernel/ftrace.c @@ -354,10 +354,13 @@ int ftrace_make_nop(struct module *mod, } rec->arch.mod = mod; } else if (mod) { - printk(KERN_ERR - "Record mod %p not equal to passed in mod %p\n", - rec->arch.mod, mod); - return -EINVAL; + if (mod != rec->arch.mod) { + printk(KERN_ERR + "Record mod %p not equal to passed in mod %p\n", + rec->arch.mod, mod); + return -EINVAL; + } + /* nothing to do if mod == rec->arch.mod */ } else mod = rec->arch.mod;
Impact: fix to module check in making nops in dynamic ftrace for PPC Paul Mackerras pointed out that the mod test in ftrace_make_nop looks wrong. It is, but it did not trigger because the logic to ftrace just happens to miss the bad case. When ftrace first changes all the calls to mcount into nops, it passes in the "mod" parameter, and the rec->arch.mod is NULL. This case assigns the rec->arch.mod to mod and succeeds. From then on, ftrace will pass in a NULL for mod and the check if mod and rec->arch.mod is the same is skipped. The failure of the current test may produce a false positive failuer, which will cause ftrace to shutdown even if the code was correct. This patch fixes the test. Reported-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Steven Rostedt <srostedt@redhat.com> --- arch/powerpc/kernel/ftrace.c | 11 +++++++---- 1 files changed, 7 insertions(+), 4 deletions(-)