Merge tag 'trace-fixes-v3.15-rc4-v2' of... (f322e262) · Commits · 戴 / test

Merge tag 'trace-fixes-v3.15-rc4-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing fixes from Steven Rostedt: "This contains two fixes. The first is a long standing bug that causes bogus data to show up in the refcnt field of the module_refcnt tracepoint. It was introduced by a merge conflict resolution back in 2.6.35-rc days. The result should be 'refcnt = incs - decs', but instead it did 'refcnt = incs + decs'. The second fix is to a bug that was introduced in this merge window that allowed for a tracepoint funcs pointer to be used after it was freed. Moving the location of where the probes are released solved the problem" * tag 'trace-fixes-v3.15-rc4-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: tracepoint: Fix use of tracepoint funcs after rcu free trace: module: Maintain a valid user count

include/trace/events/module.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -80,7 +80,7 @@ DECLARE_EVENT_CLASS(module_refcnt,

		TP_fast_assign(
		__entry->ip = ip;
		__entry->refcnt = __this_cpu_read(mod->refptr->incs) + __this_cpu_read(mod->refptr->decs);
		__entry->refcnt = __this_cpu_read(mod->refptr->incs) - __this_cpu_read(mod->refptr->decs);
		__assign_str(name, mod->name);
		),

kernel/tracepoint.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -188,7 +188,6 @@ static int tracepoint_add_func(struct tracepoint *tp,
		WARN_ON_ONCE(1);
		return PTR_ERR(old);
		}
		release_probes(old);

		/*
		* rcu_assign_pointer has a smp_wmb() which makes sure that the new
		@@ -200,6 +199,7 @@ static int tracepoint_add_func(struct tracepoint *tp,
		rcu_assign_pointer(tp->funcs, tp_funcs);
		if (!static_key_enabled(&tp->key))
		static_key_slow_inc(&tp->key);
		release_probes(old);
		return 0;
		}

		@@ -221,7 +221,6 @@ static int tracepoint_remove_func(struct tracepoint *tp,
		WARN_ON_ONCE(1);
		return PTR_ERR(old);
		}
		release_probes(old);

		if (!tp_funcs) {
		/* Removed last function */
		@@ -232,6 +231,7 @@ static int tracepoint_remove_func(struct tracepoint *tp,
		static_key_slow_dec(&tp->key);
		}
		rcu_assign_pointer(tp->funcs, tp_funcs);
		release_probes(old);
		return 0;
		}

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