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2008-02-13Linux Kernel Markers: support multiple probesMathieu Desnoyers
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 <mathieu.desnoyers@polymtl.ca> Cc: Christoph Hellwig <hch@infradead.org> Cc: Mike Mason <mmlnx@us.ibm.com> Cc: Dipankar Sarma <dipankar@in.ibm.com> Cc: David Smith <dsmith@redhat.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Cc: "Frank Ch. Eigler" <fche@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-11-14Linux Kernel Markers: fix marker mutex not taken upon module loadMathieu Desnoyers
Upon module load, we must take the markers mutex. It implies that the marker mutex must be nested inside the module mutex. It implies changing the nesting order : now the marker mutex nests inside the module mutex. Make the necessary changes to reverse the order in which the mutexes are taken. Includes some cleanup from Dave Hansen <haveblue@us.ibm.com>. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19Linux Kernel MarkersMathieu Desnoyers
The marker activation functions sits in kernel/marker.c. A hash table is used to keep track of the registered probes and armed markers, so the markers within a newly loaded module that should be active can be activated at module load time. marker_query has been removed. marker_get_first, marker_get_next and marker_release should be used as iterators on the markers. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Acked-by: "Frank Ch. Eigler" <fche@redhat.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Mike Mason <mmlnx@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>