On 05/08/2013 09:35 AM, Peter Zijlstra wrote: > On Wed, May 08, 2013 at 09:27:46AM -0400, Sasha Levin wrote: >> [snip] >> >> Hi Peter, >> >> You're right - I broke multithreading for some odd reason (mostly me being >> stupid) >> after having it working :/ >> >> It's enough to set the __thread flag on current_obj: >> >> diff --git a/tools/lib/lockdep/common.c b/tools/lib/lockdep/common.c >> index eb5e481..8ef602f 100644 >> --- a/tools/lib/lockdep/common.c >> +++ b/tools/lib/lockdep/common.c >> @@ -5,7 +5,7 @@ >> #include <unistd.h> >> #include <sys/syscall.h> >> >> -static struct task_struct current_obj; >> +static __thread struct task_struct current_obj; >> >> /* lockdep wants these */ >> bool debug_locks = true; >> >> Since we don't need any special initialization of the struct at any point. >> This >> means that the patch above is enough and we don't need to hook >> pthread_create. >> > > I tried googling but failed to find the TLS initialization rules. Are they > zero'd for each thread or copied about or what? And is this documented or > implementation behaviour? > > If its consistently zero'd then I suppose you're right and we can get away > with > just adding __thread; *phew*.
I assumed that they are zero'd because it is a global variable, and those are supposed to be zero'd. Running a quick test confirmed that they are indeed zero'd for each thread, so we're safe to just add that __thread. Thanks, Sasha -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
