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https://github.com/BobTheBlinker/android_kernel_motorola_sm6375.git
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| Filename | Latest commit message | Latest commit date |
|---|---|---|
d7b2027924
[ Upstream commit 2d093282b0d4357373497f65db6a05eb0c28b7c8 ]
When pages are removed in rb_remove_pages(), 'cpu_buffer->read' is set
to 0 in order to make sure any read iterators reset themselves. However,
this will mess 'entries' stating, see following steps:
# cd /sys/kernel/tracing/
# 1. Enlarge ring buffer prepare for later reducing:
# echo 20 > per_cpu/cpu0/buffer_size_kb
# 2. Write a log into ring buffer of cpu0:
# taskset -c 0 echo "hello1" > trace_marker
# 3. Read the log:
# cat per_cpu/cpu0/trace_pipe
<...>-332 [000] ..... 62.406844: tracing_mark_write: hello1
# 4. Stop reading and see the stats, now 0 entries, and 1 event readed:
# cat per_cpu/cpu0/stats
entries: 0
[...]
read events: 1
# 5. Reduce the ring buffer
# echo 7 > per_cpu/cpu0/buffer_size_kb
# 6. Now entries became unexpected 1 because actually no entries!!!
# cat per_cpu/cpu0/stats
entries: 1
[...]
read events: 0
To fix it, introduce 'page_removed' field to count total removed pages
since last reset, then use it to let read iterators reset themselves
instead of changing the 'read' pointer.
Link: https://lore.kernel.org/linux-trace-kernel/20230724054040.3489499-1-zhengyejian1@huawei.com
Cc: <mhiramat@kernel.org>
Cc: <vnagarnaik@google.com>
Fixes:
|
||
| .. | ||
| blktrace.c | ||
| bpf_trace.c | ||
| fgraph.c | ||
| ftrace.c | ||
| ftrace_internal.h | ||
| Kconfig | ||
| Makefile | ||
| power-traces.c | ||
| preemptirq_delay_test.c | ||
| ring_buffer.c | ||
| ring_buffer_benchmark.c | ||
| rpm-traces.c | ||
| trace.c | ||
| trace.h | ||
| trace_benchmark.c | ||
| trace_benchmark.h | ||
| trace_branch.c | ||
| trace_clock.c | ||
| trace_dynevent.c | ||
| trace_dynevent.h | ||
| trace_entries.h | ||
| trace_event_perf.c | ||
| trace_events.c | ||
| trace_events_filter.c | ||
| trace_events_filter_test.h | ||
| trace_events_hist.c | ||
| trace_events_trigger.c | ||
| trace_export.c | ||
| trace_functions.c | ||
| trace_functions_graph.c | ||
| trace_hwlat.c | ||
| trace_irqsoff.c | ||
| trace_kdb.c | ||
| trace_kprobe.c | ||
| trace_kprobe_selftest.c | ||
| trace_kprobe_selftest.h | ||
| trace_mmiotrace.c | ||
| trace_nop.c | ||
| trace_output.c | ||
| trace_output.h | ||
| trace_preemptirq.c | ||
| trace_printk.c | ||
| trace_probe.c | ||
| trace_probe.h | ||
| trace_probe_tmpl.h | ||
| trace_sched_switch.c | ||
| trace_sched_wakeup.c | ||
| trace_selftest.c | ||
| trace_selftest_dynamic.c | ||
| trace_seq.c | ||
| trace_stack.c | ||
| trace_stat.c | ||
| trace_stat.h | ||
| trace_syscalls.c | ||
| trace_uprobe.c | ||
| tracing_map.c | ||
| tracing_map.h | ||