From: Tommi Rantala tommi.t.rantala@nokia.com

mainline inclusion from mainline-5.6-rc6 commit 29b4f5f18857 category: bugfix bugzilla: 31774 CVE: NA

-------------------------------------------------

Since glibc 2.28 when running 'perf top --stdio', input handling no longer works, but hitting any key always just prints the "Mapped keys" help text.

To fix it, call clearerr() in the display_thread() loop to clear any EOF sticky errors, as instructed in the glibc NEWS file (https://sourceware.org/git/?p=glibc.git;a=blob;f=NEWS):

* All stdio functions now treat end-of-file as a sticky condition. If you read from a file until EOF, and then the file is enlarged by another process, you must call clearerr or another function with the same effect (e.g. fseek, rewind) before you can read the additional data. This corrects a longstanding C99 conformance bug. It is most likely to affect programs that use stdio to read interactive input from a terminal. (Bug #1190.)

Signed-off-by: Tommi Rantala tommi.t.rantala@nokia.com Tested-by: Arnaldo Carvalho de Melo acme@redhat.com Cc: Alexander Shishkin alexander.shishkin@linux.intel.com Cc: Jiri Olsa jolsa@redhat.com Cc: Mark Rutland mark.rutland@arm.com Cc: Namhyung Kim namhyung@kernel.org Cc: Peter Zijlstra peterz@infradead.org Link: http://lore.kernel.org/lkml/20200305083714.9381-2-tommi.t.rantala@nokia.com Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Wei Li liwei391@huawei.com Reviewed-by: Jian Cheng cj.chengjian@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- tools/perf/builtin-top.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c index 781f6cf1cda6..265c074cbe3b 100644 --- a/tools/perf/builtin-top.c +++ b/tools/perf/builtin-top.c @@ -661,7 +661,9 @@ static void *display_thread(void *arg) delay_msecs = top->delay_secs * MSEC_PER_SEC; set_term_quiet_input(&save); /* trash return*/ - getc(stdin); + clearerr(stdin); + if (poll(&stdin_poll, 1, 0) > 0) + getc(stdin);

while (!done) { perf_top__print_sym_table(top);