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author | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2020-04-01 22:44:46 -0400 |
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committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2020-04-03 11:30:50 -0400 |
commit | 8e99cf91b99bb30e16727f10ad6828741c0e992f (patch) | |
tree | ee26bf768874abdb9d63f706a8c14d136fd850a8 /tools | |
parent | 2ab2a0924b9980551ebe1c47d2a402a94efc1835 (diff) | |
download | linux-8e99cf91b99bb30e16727f10ad6828741c0e992f.tar.bz2 |
tracing: Do not allocate buffer in trace_find_next_entry() in atomic
When dumping out the trace data in latency format, a check is made to peek
at the next event to compare its timestamp to the current one, and if the
delta is of a greater size, it will add a marker showing so. But to do this,
it needs to save the current event otherwise peeking at the next event will
remove the current event. To save the event, a temp buffer is used, and if
the event is bigger than the temp buffer, the temp buffer is freed and a
bigger buffer is allocated.
This allocation is a problem when called in atomic context. The only way
this gets called via atomic context is via ftrace_dump(). Thus, use a static
buffer of 128 bytes (which covers most events), and if the event is bigger
than that, simply return NULL. The callers of trace_find_next_entry() need
to handle a NULL case, as that's what would happen if the allocation failed.
Link: https://lore.kernel.org/r/20200326091256.GR11705@shao2-debian
Fixes: ff895103a84ab ("tracing: Save off entry when peeking at next entry")
Reported-by: kernel test robot <rong.a.chen@intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'tools')
0 files changed, 0 insertions, 0 deletions