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Sun, 2 Sep 2018 13:07:07 +0000 Received: from CY4PR21MB0776.namprd21.prod.outlook.com ([fe80::7c3a:eea8:1391:1611]) by CY4PR21MB0776.namprd21.prod.outlook.com ([fe80::7c3a:eea8:1391:1611%7]) with mapi id 15.20.1143.000; Sun, 2 Sep 2018 13:07:07 +0000 From: Sasha Levin To: "stable@vger.kernel.org" , "linux-kernel@vger.kernel.org" CC: Jiri Olsa , Alexander Shishkin , David Ahern , Don Zickus , Joe Mario , Namhyung Kim , Peter Zijlstra , Arnaldo Carvalho de Melo , Sasha Levin Subject: [PATCH AUTOSEL 4.14 31/89] perf c2c report: Fix crash for empty browser Thread-Topic: [PATCH AUTOSEL 4.14 31/89] perf c2c report: Fix crash for empty browser Thread-Index: AQHUQr3NMyPpIDlhP02czLa5IZ/PPA== Date: Sun, 2 Sep 2018 13:06:45 +0000 Message-ID: <20180902064918.183387-31-alexander.levin@microsoft.com> References: <20180902064918.183387-1-alexander.levin@microsoft.com> In-Reply-To: <20180902064918.183387-1-alexander.levin@microsoft.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [52.168.54.252] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;CY4PR21MB0856;6:ZQxTDAGY22PgSuIyr66lfwIKROMEhyXnkySjZVQZNuZV6Oj2KivswFRwpjgYXZ0VjHKrBlp4qVgNXB6KMZknriR7clEvkVdOOO+oXnZVSL9UF3SL2017Ghn/qwfyGZ7X6uuATgjjFuoLUjHN5UfDxxI8aFX9aK5AKf2lZQk43LoAHhkVsOu2XAYBTWIEzNdJRCrT80PsCEcpSCpNhYBMkHnC7+BUtk20Ey7KEDQ4nNpVy3Oiubt614HnsIQ5fLWTBCuFjeQDogaUBybi95DpBdU3NhpZF6ikZ60TcjAddLn0mZCorQlx0pXX7vYUt2LXEVDo1k4/ejs4+X4t+Gp4E15j8pGGe1JkwdcOO6BsxI39//Qs1I5JhscnfjAERLV5YTQdcN0sxpz9AkQ2JTV8DXkIE0u9TvQCOlKatfTLAcyKK0JOMqyRE8Kzp+htZ+9PIQ7jBiMFMzqFwnJsHH1S1Q==;5:BhRFNhQbvfPGahnuQmlgU2sEQB5pvNujSeGnMTAf7R79mi8xdPYnGSJREFo0alBWUMrbbofekhtct/V/F8mfTRplMdBqXyf1RKNbLcjns72sgjYmMs9GBqIE6d2s93AOyaZ7u8TICgkFGQsq3pPxRRCcyKILWKBZPUTMURpBPkU=;7:Z2JSz6cYNajV7mGCATyBDtXGWxHTqb6QMZCqewI76hfSyKZs0Ha1eclqRz5ou05IxM6Y88Pbje7ZFVqzWXyro1F6E9734fmuWSsT2Oxl11hdTtatwrCOTYNg/gnGTUn6IlheItRTuKPmnla9JjtlRrpbO68oFMIucj++djKaOza4mJhSLe2ywTXWwFcd3dbfvcGdVRqD9VI/O4t4YAlKIMF5TqSzIhPXDBgpe0cTXB4zQX3rcleJ4Fy1W7X+zx+F x-ms-office365-filtering-correlation-id: 6a8a992b-769a-44d0-88cf-08d610d4fc64 x-ms-office365-filtering-ht: Tenant x-microsoft-antispam: BCL:0;PCL:0;RULEID:(7020095)(4652040)(4534165)(4627221)(201703031133081)(201702281549075)(5600074)(711020)(4618075)(2017052603328)(7193020);SRVR:CY4PR21MB0856; 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received-spf: None (protection.outlook.com: microsoft.com does not designate permitted sender hosts) x-microsoft-antispam-message-info: H/xtKy3SIDV9Ml/THDLqKWIqj9pLFQpVx4OLxVOyu/AtC5fSbM5p4hzmimNfV6LVvg1qsGaUebLtZVTETkwPFDUF2A9QG2FayjfG7f13OHAJbxlqNap8IPeUBggFmADFnLNKevvTSUfY7F8O9ipRwlvXxx6vwF69GnBowgWufGWcqD9PQESAE1ngvmtIZzbMbyaiwGWzCkgKvNn5NkM/BWZ+L0YLoZBNp+iCfKbEoq3+74/DF4vd7MQ/g/beOfz7t2b2aRcfZCHME5C9m5BuuaKa4m2joXQeezGzVxBBXbaaB38LjiiLEC/VH6XAyC4HrtVcAYnvgBu2ePL/qFdgm7B/dt1hslK1BfZFSAxMQ5k= spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-Network-Message-Id: 6a8a992b-769a-44d0-88cf-08d610d4fc64 X-MS-Exchange-CrossTenant-originalarrivaltime: 02 Sep 2018 13:06:45.7282 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY4PR21MB0856 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jiri Olsa [ Upstream commit 73978332572ccf5e364c31e9a70ba953f8202b46 ] '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 Tested-by: Arnaldo Carvalho de Melo Cc: Alexander Shishkin Cc: David Ahern Cc: Don Zickus Cc: Joe Mario Cc: Namhyung Kim Cc: Peter Zijlstra 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 Signed-off-by: Sasha Levin --- tools/perf/builtin-c2c.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c index 3479a1bc7caa..fb76423022e8 100644 --- a/tools/perf/builtin-c2c.c +++ b/tools/perf/builtin-c2c.c @@ -2229,6 +2229,9 @@ static int perf_c2c__browse_cacheline(struct hist_ent= ry *he) " s Togle full lenght of symbol and source line columns \n" " q Return back to cacheline list \n"; =20 + if (!he) + return 0; + /* Display compact version first. */ c2c.symbol_full =3D false; =20 --=20 2.17.1