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authorJiri Olsa <jolsa@kernel.org>2018-07-24 08:20:08 +0200
committerArnaldo Carvalho de Melo <acme@redhat.com>2018-07-31 10:53:20 -0300
commit73978332572ccf5e364c31e9a70ba953f8202b46 (patch)
tree2cad98657b6247ef0f4bfa20f25d55da541f8476 /tools
parentaa90f9f9554616d5738f7bedb4a8f0e5e14d1bc6 (diff)
downloadlinux-73978332572ccf5e364c31e9a70ba953f8202b46.tar.bz2
perf c2c report: Fix crash for empty browser
'perf c2c' scans read/write accesses and tries to find false sharing cases, so when the events it wants were not asked for or ended up not taking place, we get no histograms. So do not try to display entry details if there's not any. Currently this ends up in crash: $ perf c2c report # then press 'd' perf: Segmentation fault $ Committer testing: Before: Record a perf.data file without events of interest to 'perf c2c report', then call it and press 'd': # perf record sleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.001 MB perf.data (6 samples) ] # perf c2c report perf: Segmentation fault -------- backtrace -------- perf[0x5b1d2a] /lib64/libc.so.6(+0x346df)[0x7fcb566e36df] perf[0x46fcae] perf[0x4a9f1e] perf[0x4aa220] perf(main+0x301)[0x42c561] /lib64/libc.so.6(__libc_start_main+0xe9)[0x7fcb566cff29] perf(_start+0x29)[0x42c999] # After the patch the segfault doesn't take place, a follow up patch to tell the user why nothing changes when 'd' is pressed would be good. Reported-by: rodia@autistici.org Signed-off-by: Jiri Olsa <jolsa@kernel.org> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: David Ahern <dsahern@gmail.com> Cc: Don Zickus <dzickus@redhat.com> Cc: Joe Mario <jmario@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Fixes: f1c5fd4d0bb9 ("perf c2c report: Add TUI cacheline browser") Link: http://lkml.kernel.org/r/20180724062008.26126-1-jolsa@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools')
-rw-r--r--tools/perf/builtin-c2c.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c
index f2ea85ee573f..f3aa9d02a5ab 100644
--- a/tools/perf/builtin-c2c.c
+++ b/tools/perf/builtin-c2c.c
@@ -2349,6 +2349,9 @@ static int perf_c2c__browse_cacheline(struct hist_entry *he)
" s Toggle full length of symbol and source line columns \n"
" q Return back to cacheline list \n";
+ if (!he)
+ return 0;
+
/* Display compact version first. */
c2c.symbol_full = false;