Commit-ID: 5b1dbd17c0dee679b154ce47f534677b7e0f7ad6 Gitweb: http://git.kernel.org/tip/5b1dbd17c0dee679b154ce47f534677b7e0f7ad6 Author: Alexander Shishkin <[email protected]> AuthorDate: Tue, 21 Apr 2015 16:16:16 +0300 Committer: Ingo Molnar <[email protected]> CommitDate: Wed, 27 May 2015 09:17:47 +0200
perf/x86/intel/pt: Document pt_buffer_reset_offsets() Currently, the description of pt_buffer_reset_offsets() lacks information about its calling constraints and ordering with regards to other buffer management functions. Add a clarification about when this function has to be called. Signed-off-by: Alexander Shishkin <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Paul Mackerras <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Link: http://lkml.kernel.org/r/1429622177-22843-5-git-send-email-alexander.shish...@linux.intel.com Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/kernel/cpu/perf_event_intel_pt.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/perf_event_intel_pt.c b/arch/x86/kernel/cpu/perf_event_intel_pt.c index b2746ea..40ba5e4 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_pt.c +++ b/arch/x86/kernel/cpu/perf_event_intel_pt.c @@ -705,7 +705,14 @@ static void pt_buffer_setup_topa_index(struct pt_buffer *buf) * @head: Write pointer (aux_head) from AUX buffer. * * Find the ToPA table and entry corresponding to given @head and set buffer's - * "current" pointers accordingly. + * "current" pointers accordingly. This is done after we have obtained the + * current aux_head position from a successful call to perf_aux_output_begin() + * to make sure the hardware is writing to the right place. + * + * This function modifies buf::{cur,cur_idx,output_off} that will be programmed + * into PT msrs when the tracing is enabled and buf::head and buf::data_size, + * which are used to determine INT and STOP markers' locations by a subsequent + * call to pt_buffer_reset_markers(). */ static void pt_buffer_reset_offsets(struct pt_buffer *buf, unsigned long head) { -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
