diff options
| author | Tom Zanussi <[email protected]> | 2019-02-04 15:07:24 -0600 |
|---|---|---|
| committer | Steven Rostedt (VMware) <[email protected]> | 2019-03-05 08:47:46 -0500 |
| commit | 9f0bbf3115ca9f91f43b7c74e9ac7d79f47fc6c2 (patch) | |
| tree | bc91b05a3507119c615c73a47b7bcbaedb4b39a0 /include/linux/fpga/fpga-mgr.h | |
| parent | ed581aaf99be10883c8364df16bd80a7b8f72efc (diff) | |
tracing: Use strncpy instead of memcpy for string keys in hist triggers
Because there may be random garbage beyond a string's null terminator,
it's not correct to copy the the complete character array for use as a
hist trigger key. This results in multiple histogram entries for the
'same' string key.
So, in the case of a string key, use strncpy instead of memcpy to
avoid copying in the extra bytes.
Before, using the gdbus entries in the following hist trigger as an
example:
# echo 'hist:key=comm' > /sys/kernel/debug/tracing/events/sched/sched_waking/trigger
# cat /sys/kernel/debug/tracing/events/sched/sched_waking/hist
...
{ comm: ImgDecoder #4 } hitcount: 203
{ comm: gmain } hitcount: 213
{ comm: gmain } hitcount: 216
{ comm: StreamTrans #73 } hitcount: 221
{ comm: mozStorage #3 } hitcount: 230
{ comm: gdbus } hitcount: 233
{ comm: StyleThread#5 } hitcount: 253
{ comm: gdbus } hitcount: 256
{ comm: gdbus } hitcount: 260
{ comm: StyleThread#4 } hitcount: 271
...
# cat /sys/kernel/debug/tracing/events/sched/sched_waking/hist | egrep gdbus | wc -l
51
After:
# cat /sys/kernel/debug/tracing/events/sched/sched_waking/hist | egrep gdbus | wc -l
1
Link: http://lkml.kernel.org/r/50c35ae1267d64eee975b8125e151e600071d4dc.1549309756.git.tom.zanussi@linux.intel.com
Cc: Namhyung Kim <[email protected]>
Cc: [email protected]
Fixes: 79e577cbce4c4 ("tracing: Support string type key properly")
Signed-off-by: Tom Zanussi <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>
Diffstat (limited to 'include/linux/fpga/fpga-mgr.h')
0 files changed, 0 insertions, 0 deletions