Em Fri, Feb 17, 2017 at 12:10:25PM +0100, Jan Stancek escreveu: > When build_cpu_topo() encounters offline/absent CPUs, > it fails to find any sysfs entries and returns failure. > This leads to build_cpu_topology() and write_cpu_topology() > failing as well. > > Because HEADER_CPU_TOPOLOGY has not been written, read leaves > cpu_topology_map NULL and we get NULL ptr deref at: > > ... > cmd_test > __cmd_test > test_and_print > run_test > test_session_topology > check_cpu_topology > > 36: Session topology : > --- start ---
Please add two spaces before tool output, so that we can avoid breaking scripts looking for --- as separator of patch message from patch content. Also look at 'git log file/you/are/modifying' to see the patch log style, for this one I'm changing to: perf header: Make build_cpu_topology skip offline/absent CPUs Thanks, - Arnaldo > test child forked, pid 14902 > templ file: /tmp/perf-test-4CKocW > failed to write feature HEADER_CPU_TOPOLOGY > perf: Segmentation fault > Obtained 9 stack frames. > ./perf(sighandler_dump_stack+0x41) [0x5095f1] > /lib64/libc.so.6(+0x35250) [0x7f4b7c3c9250] > ./perf(test_session_topology+0x1db) [0x490ceb] > ./perf() [0x475b68] > ./perf(cmd_test+0x5b9) [0x4763c9] > ./perf() [0x4945a3] > ./perf(main+0x69f) [0x427e8f] > /lib64/libc.so.6(__libc_start_main+0xf5) [0x7f4b7c3b5b35] > ./perf() [0x427fb9] > test child interrupted > ---- end ---- > Session topology: FAILED! > > This patch makes build_cpu_topology() skip offline/absent CPUs, > by checking their presence against cpu_map built from online CPUs. > > Signed-off-by: Jan Stancek <[email protected]> > --- > tools/perf/util/header.c | 19 ++++++++++++++++--- > 1 file changed, 16 insertions(+), 3 deletions(-) > > Changes in v3: > - make ret = -1 by default, so we fail in case build_cpu_topo > doesn't run at all > > diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c > index d89c9c7ef4e5..ca0f12fb5fd3 100644 > --- a/tools/perf/util/header.c > +++ b/tools/perf/util/header.c > @@ -503,24 +503,31 @@ static void free_cpu_topo(struct cpu_topo *tp) > > static struct cpu_topo *build_cpu_topology(void) > { > - struct cpu_topo *tp; > + struct cpu_topo *tp = NULL; > void *addr; > u32 nr, i; > size_t sz; > long ncpus; > int ret = -1; > + struct cpu_map *map; > > ncpus = sysconf(_SC_NPROCESSORS_CONF); > if (ncpus < 0) > return NULL; > > + /* build online CPU map */ > + map = cpu_map__new(NULL); > + if (map == NULL) { > + pr_debug("failed to get system cpumap\n"); > + return NULL; > + } > + > nr = (u32)(ncpus & UINT_MAX); > > sz = nr * sizeof(char *); > - > addr = calloc(1, sizeof(*tp) + 2 * sz); > if (!addr) > - return NULL; > + goto out_free; > > tp = addr; > tp->cpu_nr = nr; > @@ -530,10 +537,16 @@ static struct cpu_topo *build_cpu_topology(void) > tp->thread_siblings = addr; > > for (i = 0; i < nr; i++) { > + if (!cpu_map__has(map, i)) > + continue; > + > ret = build_cpu_topo(tp, i); > if (ret < 0) > break; > } > + > +out_free: > + cpu_map__put(map); > if (ret) { > free_cpu_topo(tp); > tp = NULL; > -- > 1.8.3.1
