From fb40bd78b0f91b274879cf5db8facd1e04b6052e Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Wed, 13 Feb 2008 15:03:37 -0800 Subject: Linux Kernel Markers: support multiple probes RCU style multiple probes support for the Linux Kernel Markers. Common case (one probe) is still fast and does not require dynamic allocation or a supplementary pointer dereference on the fast path. - Move preempt disable from the marker site to the callback. Since we now have an internal callback, move the preempt disable/enable to the callback instead of the marker site. Since the callback change is done asynchronously (passing from a handler that supports arguments to a handler that does not setup the arguments is no arguments are passed), we can safely update it even if it is outside the preempt disable section. - Move probe arm to probe connection. Now, a connected probe is automatically armed. Remove MARK_MAX_FORMAT_LEN, unused. This patch modifies the Linux Kernel Markers API : it removes the probe "arm/disarm" and changes the probe function prototype : it now expects a va_list * instead of a "...". If we want to have more than one probe connected to a marker at a given time (LTTng, or blktrace, ssytemtap) then we need this patch. Without it, connecting a second probe handler to a marker will fail. It allow us, for instance, to do interesting combinations : Do standard tracing with LTTng and, eventually, to compute statistics with SystemTAP, or to have a special trigger on an event that would call a systemtap script which would stop flight recorder tracing. Signed-off-by: Mathieu Desnoyers Cc: Christoph Hellwig Cc: Mike Mason Cc: Dipankar Sarma Cc: David Smith Cc: "Paul E. McKenney" Cc: "Frank Ch. Eigler" Cc: Steven Rostedt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/module.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) (limited to 'kernel/module.c') diff --git a/kernel/module.c b/kernel/module.c index 4202da97a1da..92595bad3812 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2038,7 +2038,7 @@ static struct module *load_module(void __user *umod, #ifdef CONFIG_MARKERS if (!mod->taints) marker_update_probe_range(mod->markers, - mod->markers + mod->num_markers, NULL, NULL); + mod->markers + mod->num_markers); #endif err = module_finalize(hdr, sechdrs, mod); if (err < 0) @@ -2564,7 +2564,7 @@ EXPORT_SYMBOL(struct_module); #endif #ifdef CONFIG_MARKERS -void module_update_markers(struct module *probe_module, int *refcount) +void module_update_markers(void) { struct module *mod; @@ -2572,8 +2572,7 @@ void module_update_markers(struct module *probe_module, int *refcount) list_for_each_entry(mod, &modules, list) if (!mod->taints) marker_update_probe_range(mod->markers, - mod->markers + mod->num_markers, - probe_module, refcount); + mod->markers + mod->num_markers); mutex_unlock(&module_mutex); } #endif -- cgit