From: Dan Carpenter <dan.carpenter@oracle.com>
To: kbuild@lists.01.org
Subject: Re: [RFC][PATCH] ring-buffer: Have nested events still record running time stamp
Date: Fri, 26 Jun 2020 11:44:47 +0300 [thread overview]
Message-ID: <20200626084447.GH2549@kadam> (raw)
In-Reply-To: <20200625094454.732790f7@oasis.local.home>
[-- Attachment #1: Type: text/plain, Size: 14932 bytes --]
Hi Steven,
[FYI, it's a private test report for your RFC patch.]
[auto build test WARNING on tip/perf/core]
[also build test WARNING on linux/master linus/master v5.8-rc2 next-20200625]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use as documented in
https://git-scm.com/docs/git-format-patch]
url: https://github.com/0day-ci/linux/commits/Steven-Rostedt/ring-buffer-Have-nested-events-still-record-running-time-stamp/20200625-214744
base: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git bb42b3d39781d7fcd3be7f9f9bf11b6661b5fdf1
config: x86_64-randconfig-m001-20200624 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-13) 9.3.0
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
smatch warnings:
kernel/trace/ring_buffer.c:3046 __rb_reserve_next() error: uninitialized symbol 'delta'.
# https://github.com/0day-ci/linux/commit/9a8ccc67a4f2747143e5fadf7404172d9608cdb8
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout 9a8ccc67a4f2747143e5fadf7404172d9608cdb8
vim +/delta +3046 kernel/trace/ring_buffer.c
6634ff26cce2da0 Steven Rostedt 2009-05-06 2903 static struct ring_buffer_event *
6634ff26cce2da0 Steven Rostedt 2009-05-06 2904 __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
fcc742eaad7cbcb Steven Rostedt (Red Hat 2015-05-28 2905) struct rb_event_info *info)
6634ff26cce2da0 Steven Rostedt 2009-05-06 2906 {
6634ff26cce2da0 Steven Rostedt 2009-05-06 2907 struct ring_buffer_event *event;
fcc742eaad7cbcb Steven Rostedt (Red Hat 2015-05-28 2908) struct buffer_page *tail_page;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2909) unsigned long tail, write, w, next;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2910) u64 delta, before, after;
^^^^^
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 2911)
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2912) /* Don't let the compiler play games with cpu_buffer->tail_page */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2913) tail_page = info->tail_page = READ_ONCE(cpu_buffer->tail_page);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2914)
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2915) /*A*/ w = local_read(&tail_page->write) & RB_WRITE_MASK;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2916) barrier();
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2917) before = READ_ONCE(cpu_buffer->before_stamp);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2918) after = local64_read(&cpu_buffer->write_stamp);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2919) /*
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2920) * If preempting an event time update, we may need absolute timestamp.
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2921) * Don't bother if this is the start of a new page (w == 0).
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2922) */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2923) if (unlikely(before != after && w))
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2924) info->add_timestamp = RB_ADD_STAMP_FORCE;
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 2925) /*
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 2926) * If the time delta since the last event is too big to
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 2927) * hold in the time field of the event, then we append a
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 2928) * TIME EXTEND event ahead of the data event.
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 2929) */
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 2930) if (unlikely(info->add_timestamp))
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 2931) info->length += RB_LEN_TIME_EXTEND;
69d1b839f7eee34 Steven Rostedt 2010-10-07 2932
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2933) next = READ_ONCE(cpu_buffer->next_write);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2934) WRITE_ONCE(cpu_buffer->next_write, w + info->length);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2935)
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2936) info->ts = rb_time_stamp(cpu_buffer->buffer);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2937) /*B*/ WRITE_ONCE(cpu_buffer->before_stamp, info->ts);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2938)
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2939) /*C*/ write = local_add_return(info->length, &tail_page->write);
77ae365eca89506 Steven Rostedt 2009-03-27 2940
77ae365eca89506 Steven Rostedt 2009-03-27 2941 /* set write to only the index of the write */
77ae365eca89506 Steven Rostedt 2009-03-27 2942 write &= RB_WRITE_MASK;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2943)
fcc742eaad7cbcb Steven Rostedt (Red Hat 2015-05-28 2944) tail = write - info->length;
6634ff26cce2da0 Steven Rostedt 2009-05-06 2945
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2946) /* See if we shot pass the end of this buffer page */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2947) if (unlikely(write > BUF_PAGE_SIZE)) {
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2948) if (tail != w) {
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2949) /* before and after may now different, fix it up*/
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2950) before = READ_ONCE(cpu_buffer->before_stamp);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2951) after = local64_read(&cpu_buffer->write_stamp);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2952) if (before != after)
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2953) (void)cmpxchg(&cpu_buffer->before_stamp, before, after);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2954) }
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2955) return rb_move_tail(cpu_buffer, tail, info);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2956) }
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2957)
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2958) if (likely(tail == w)) {
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2959) u64 save_before;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2960)
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2961) /* Nothing preempted us between A and C */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2962) /*D*/ local64_set(&cpu_buffer->write_stamp, info->ts);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2963) barrier();
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2964) /*E*/ save_before = READ_ONCE(cpu_buffer->before_stamp);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2965) if (likely(info->add_timestamp != RB_ADD_STAMP_FORCE)) {
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2966) /* This did not preempt any time update */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2967) info->delta = info->ts - after;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2968) } else {
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2969) /* SLOW PATH */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2970) if (w == next) {
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2971) /* before is the time stamp of the last event */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2972) info->delta = info->ts - before;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2973) info->add_timestamp = RB_ADD_STAMP_NORMAL;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2974) } else {
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2975) /* Last event time stamp is lost, inject absolute. */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2976) info->delta = info->ts;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2977) }
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2978) }
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2979) barrier();
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2980) if (unlikely(info->ts != save_before)) {
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2981) /* SLOW PATH - Preempted between C and E */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2982)
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2983) after = local64_read(&cpu_buffer->write_stamp);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2984) /* Write stamp must only go forward */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2985) if (save_before > after) {
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2986) /*
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2987) * We do not care about the result, only that
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2988) * it gets updated atomically.
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2989) */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2990) (void)local64_cmpxchg(&cpu_buffer->write_stamp, after, save_before);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2991) }
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2992) }
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2993) } else {
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2994) u64 ts;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2995) /* SLOW PATH - Preempted between A and C */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2996) after = local64_read(&cpu_buffer->write_stamp);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2997) ts = rb_time_stamp(cpu_buffer->buffer);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2998) barrier();
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2999) /*E*/ if (write == (local_read(&tail_page->write) & RB_WRITE_MASK) &&
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3000) after < ts) {
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3001) /* Nothing came after this event between C and E */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3002) info->delta = ts - after;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3003) (void)local64_cmpxchg(&cpu_buffer->write_stamp, after, info->ts);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3004) info->ts = ts;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3005) } else {
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3006) /*
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3007) * Preempted beween C and E:
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3008) * Lost the previous events time stamp. Just set the
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3009) * delta to zero, and this will be the same time as
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3010) * the veent this event preempted. And the events that
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3011) * came after this will still be correct (as they would
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3012) * have built their delta on the previous event.
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3013) */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3014) info->delta = 0;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3015) }
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3016) if (info->add_timestamp == RB_ADD_STAMP_FORCE)
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3017) info->add_timestamp = RB_ADD_STAMP_NORMAL;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3018) }
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3019)
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 3020) /*
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 3021) * If this is the first commit on the page, then it has the same
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 3022) * timestamp as the page itself.
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 3023) */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3024) if (unlikely(!tail && info->add_timestamp != RB_ADD_STAMP_FORCE &&
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3025) !ring_buffer_time_stamp_abs(cpu_buffer->buffer)))
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 3026) info->delta = 0;
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 3027)
6634ff26cce2da0 Steven Rostedt 2009-05-06 3028 /* We reserved something on the buffer */
6634ff26cce2da0 Steven Rostedt 2009-05-06 3029
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 3030) event = __rb_page_index(tail_page, tail);
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 3031) rb_update_event(cpu_buffer, event, info);
a4543a2fa9ef31d Steven Rostedt (Red Hat 2015-05-29 3032)
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 3033) local_inc(&tail_page->entries);
6634ff26cce2da0 Steven Rostedt 2009-05-06 3034
6634ff26cce2da0 Steven Rostedt 2009-05-06 3035 /*
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 3036) * If this is the first commit on the page, then update
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 3037) * its timestamp.
6634ff26cce2da0 Steven Rostedt 2009-05-06 3038 */
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 3039) if (!tail)
fcc742eaad7cbcb Steven Rostedt (Red Hat 2015-05-28 3040) tail_page->page->time_stamp = info->ts;
6634ff26cce2da0 Steven Rostedt 2009-05-06 3041
c64e148a3be3cb7 Vaibhav Nagarnaik 2011-08-16 3042 /* account for these added bytes */
fcc742eaad7cbcb Steven Rostedt (Red Hat 2015-05-28 3043) local_add(info->length, &cpu_buffer->entries_bytes);
c64e148a3be3cb7 Vaibhav Nagarnaik 2011-08-16 3044
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3045) /* This will be used to update write stamp */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 @3046) info->delta = delta;
^^^^^
"delta" is never initialized.
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3047)
6634ff26cce2da0 Steven Rostedt 2009-05-06 3048 return event;
6634ff26cce2da0 Steven Rostedt 2009-05-06 3049 }
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org
[-- Attachment #2: config.gz --]
[-- Type: application/gzip, Size: 33424 bytes --]
WARNING: multiple messages have this Message-ID (diff)
From: Dan Carpenter <dan.carpenter@oracle.com>
To: kbuild-all@lists.01.org
Subject: Re: [RFC][PATCH] ring-buffer: Have nested events still record running time stamp
Date: Fri, 26 Jun 2020 11:44:47 +0300 [thread overview]
Message-ID: <20200626084447.GH2549@kadam> (raw)
In-Reply-To: <20200625094454.732790f7@oasis.local.home>
[-- Attachment #1: Type: text/plain, Size: 14932 bytes --]
Hi Steven,
[FYI, it's a private test report for your RFC patch.]
[auto build test WARNING on tip/perf/core]
[also build test WARNING on linux/master linus/master v5.8-rc2 next-20200625]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use as documented in
https://git-scm.com/docs/git-format-patch]
url: https://github.com/0day-ci/linux/commits/Steven-Rostedt/ring-buffer-Have-nested-events-still-record-running-time-stamp/20200625-214744
base: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git bb42b3d39781d7fcd3be7f9f9bf11b6661b5fdf1
config: x86_64-randconfig-m001-20200624 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-13) 9.3.0
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
smatch warnings:
kernel/trace/ring_buffer.c:3046 __rb_reserve_next() error: uninitialized symbol 'delta'.
# https://github.com/0day-ci/linux/commit/9a8ccc67a4f2747143e5fadf7404172d9608cdb8
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout 9a8ccc67a4f2747143e5fadf7404172d9608cdb8
vim +/delta +3046 kernel/trace/ring_buffer.c
6634ff26cce2da0 Steven Rostedt 2009-05-06 2903 static struct ring_buffer_event *
6634ff26cce2da0 Steven Rostedt 2009-05-06 2904 __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
fcc742eaad7cbcb Steven Rostedt (Red Hat 2015-05-28 2905) struct rb_event_info *info)
6634ff26cce2da0 Steven Rostedt 2009-05-06 2906 {
6634ff26cce2da0 Steven Rostedt 2009-05-06 2907 struct ring_buffer_event *event;
fcc742eaad7cbcb Steven Rostedt (Red Hat 2015-05-28 2908) struct buffer_page *tail_page;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2909) unsigned long tail, write, w, next;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2910) u64 delta, before, after;
^^^^^
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 2911)
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2912) /* Don't let the compiler play games with cpu_buffer->tail_page */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2913) tail_page = info->tail_page = READ_ONCE(cpu_buffer->tail_page);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2914)
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2915) /*A*/ w = local_read(&tail_page->write) & RB_WRITE_MASK;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2916) barrier();
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2917) before = READ_ONCE(cpu_buffer->before_stamp);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2918) after = local64_read(&cpu_buffer->write_stamp);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2919) /*
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2920) * If preempting an event time update, we may need absolute timestamp.
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2921) * Don't bother if this is the start of a new page (w == 0).
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2922) */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2923) if (unlikely(before != after && w))
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2924) info->add_timestamp = RB_ADD_STAMP_FORCE;
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 2925) /*
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 2926) * If the time delta since the last event is too big to
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 2927) * hold in the time field of the event, then we append a
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 2928) * TIME EXTEND event ahead of the data event.
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 2929) */
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 2930) if (unlikely(info->add_timestamp))
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 2931) info->length += RB_LEN_TIME_EXTEND;
69d1b839f7eee34 Steven Rostedt 2010-10-07 2932
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2933) next = READ_ONCE(cpu_buffer->next_write);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2934) WRITE_ONCE(cpu_buffer->next_write, w + info->length);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2935)
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2936) info->ts = rb_time_stamp(cpu_buffer->buffer);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2937) /*B*/ WRITE_ONCE(cpu_buffer->before_stamp, info->ts);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2938)
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2939) /*C*/ write = local_add_return(info->length, &tail_page->write);
77ae365eca89506 Steven Rostedt 2009-03-27 2940
77ae365eca89506 Steven Rostedt 2009-03-27 2941 /* set write to only the index of the write */
77ae365eca89506 Steven Rostedt 2009-03-27 2942 write &= RB_WRITE_MASK;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2943)
fcc742eaad7cbcb Steven Rostedt (Red Hat 2015-05-28 2944) tail = write - info->length;
6634ff26cce2da0 Steven Rostedt 2009-05-06 2945
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2946) /* See if we shot pass the end of this buffer page */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2947) if (unlikely(write > BUF_PAGE_SIZE)) {
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2948) if (tail != w) {
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2949) /* before and after may now different, fix it up*/
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2950) before = READ_ONCE(cpu_buffer->before_stamp);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2951) after = local64_read(&cpu_buffer->write_stamp);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2952) if (before != after)
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2953) (void)cmpxchg(&cpu_buffer->before_stamp, before, after);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2954) }
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2955) return rb_move_tail(cpu_buffer, tail, info);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2956) }
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2957)
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2958) if (likely(tail == w)) {
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2959) u64 save_before;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2960)
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2961) /* Nothing preempted us between A and C */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2962) /*D*/ local64_set(&cpu_buffer->write_stamp, info->ts);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2963) barrier();
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2964) /*E*/ save_before = READ_ONCE(cpu_buffer->before_stamp);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2965) if (likely(info->add_timestamp != RB_ADD_STAMP_FORCE)) {
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2966) /* This did not preempt any time update */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2967) info->delta = info->ts - after;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2968) } else {
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2969) /* SLOW PATH */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2970) if (w == next) {
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2971) /* before is the time stamp of the last event */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2972) info->delta = info->ts - before;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2973) info->add_timestamp = RB_ADD_STAMP_NORMAL;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2974) } else {
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2975) /* Last event time stamp is lost, inject absolute. */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2976) info->delta = info->ts;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2977) }
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2978) }
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2979) barrier();
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2980) if (unlikely(info->ts != save_before)) {
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2981) /* SLOW PATH - Preempted between C and E */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2982)
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2983) after = local64_read(&cpu_buffer->write_stamp);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2984) /* Write stamp must only go forward */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2985) if (save_before > after) {
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2986) /*
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2987) * We do not care about the result, only that
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2988) * it gets updated atomically.
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2989) */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2990) (void)local64_cmpxchg(&cpu_buffer->write_stamp, after, save_before);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2991) }
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2992) }
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2993) } else {
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2994) u64 ts;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2995) /* SLOW PATH - Preempted between A and C */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2996) after = local64_read(&cpu_buffer->write_stamp);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2997) ts = rb_time_stamp(cpu_buffer->buffer);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2998) barrier();
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 2999) /*E*/ if (write == (local_read(&tail_page->write) & RB_WRITE_MASK) &&
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3000) after < ts) {
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3001) /* Nothing came after this event between C and E */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3002) info->delta = ts - after;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3003) (void)local64_cmpxchg(&cpu_buffer->write_stamp, after, info->ts);
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3004) info->ts = ts;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3005) } else {
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3006) /*
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3007) * Preempted beween C and E:
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3008) * Lost the previous events time stamp. Just set the
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3009) * delta to zero, and this will be the same time as
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3010) * the veent this event preempted. And the events that
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3011) * came after this will still be correct (as they would
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3012) * have built their delta on the previous event.
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3013) */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3014) info->delta = 0;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3015) }
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3016) if (info->add_timestamp == RB_ADD_STAMP_FORCE)
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3017) info->add_timestamp = RB_ADD_STAMP_NORMAL;
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3018) }
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3019)
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 3020) /*
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 3021) * If this is the first commit on the page, then it has the same
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 3022) * timestamp as the page itself.
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 3023) */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3024) if (unlikely(!tail && info->add_timestamp != RB_ADD_STAMP_FORCE &&
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3025) !ring_buffer_time_stamp_abs(cpu_buffer->buffer)))
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 3026) info->delta = 0;
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 3027)
6634ff26cce2da0 Steven Rostedt 2009-05-06 3028 /* We reserved something on the buffer */
6634ff26cce2da0 Steven Rostedt 2009-05-06 3029
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 3030) event = __rb_page_index(tail_page, tail);
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 3031) rb_update_event(cpu_buffer, event, info);
a4543a2fa9ef31d Steven Rostedt (Red Hat 2015-05-29 3032)
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 3033) local_inc(&tail_page->entries);
6634ff26cce2da0 Steven Rostedt 2009-05-06 3034
6634ff26cce2da0 Steven Rostedt 2009-05-06 3035 /*
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 3036) * If this is the first commit on the page, then update
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 3037) * its timestamp.
6634ff26cce2da0 Steven Rostedt 2009-05-06 3038 */
b7dc42fd79390c0 Steven Rostedt (Red Hat 2015-09-03 3039) if (!tail)
fcc742eaad7cbcb Steven Rostedt (Red Hat 2015-05-28 3040) tail_page->page->time_stamp = info->ts;
6634ff26cce2da0 Steven Rostedt 2009-05-06 3041
c64e148a3be3cb7 Vaibhav Nagarnaik 2011-08-16 3042 /* account for these added bytes */
fcc742eaad7cbcb Steven Rostedt (Red Hat 2015-05-28 3043) local_add(info->length, &cpu_buffer->entries_bytes);
c64e148a3be3cb7 Vaibhav Nagarnaik 2011-08-16 3044
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3045) /* This will be used to update write stamp */
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 @3046) info->delta = delta;
^^^^^
"delta" is never initialized.
9a8ccc67a4f2747 Steven Rostedt (VMware 2020-06-25 3047)
6634ff26cce2da0 Steven Rostedt 2009-05-06 3048 return event;
6634ff26cce2da0 Steven Rostedt 2009-05-06 3049 }
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org
[-- Attachment #2: config.gz --]
[-- Type: application/gzip, Size: 33424 bytes --]
next prev parent reply other threads:[~2020-06-26 8:44 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-25 13:44 [RFC][PATCH] ring-buffer: Have nested events still record running time stamp Steven Rostedt
2020-06-25 13:53 ` Mathieu Desnoyers
2020-06-25 14:37 ` Steven Rostedt
2020-06-25 16:42 ` Korben Rusek
2020-06-25 18:12 ` Steven Rostedt
2020-06-25 17:55 ` Mathieu Desnoyers
2020-06-25 18:35 ` Steven Rostedt
2020-06-25 19:35 ` Mathieu Desnoyers
2020-06-25 19:58 ` Steven Rostedt
2020-06-26 2:36 ` Steven Rostedt
2020-06-26 3:35 ` Steven Rostedt
2020-06-26 13:58 ` Steven Rostedt
2020-06-26 18:13 ` Mathieu Desnoyers
2020-06-26 18:58 ` Steven Rostedt
2020-06-26 19:39 ` Steven Rostedt
2020-06-30 0:21 ` Steven Rostedt
2020-06-30 3:13 ` Mathieu Desnoyers
2020-06-30 3:26 ` Steven Rostedt
2020-06-25 19:04 ` Steven Rostedt
2020-06-25 19:58 ` Mathieu Desnoyers
2020-06-25 20:42 ` Steven Rostedt
2020-06-25 19:09 ` Steven Rostedt
2020-06-25 20:03 ` Mathieu Desnoyers
2020-06-25 18:02 ` kernel test robot
2020-06-25 18:09 ` Steven Rostedt
2020-06-25 18:56 ` kernel test robot
2020-06-26 8:44 ` Dan Carpenter [this message]
2020-06-26 8:44 ` Dan Carpenter
2020-06-28 8:59 ` kernel test robot
-- strict thread matches above, loose matches on Subject: below --
2020-06-25 17:10 kernel test robot
2020-06-25 20:43 kernel test robot
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