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Rao" To: Cc: Arnaldo Carvalho de Melo , Masami Hiramatsu , "Aneesh Kumar K.V" Subject: [PATCH] tools/perf probe: Print a hint if adding a probe fails Date: Thu, 10 Jun 2021 15:14:42 +0530 Message-Id: <20210610094442.1602714-1-naveen.n.rao@linux.vnet.ibm.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: WW-ZiUoUVEdnndFPnjPYJV6sqJmYIdta X-Proofpoint-ORIG-GUID: WW-ZiUoUVEdnndFPnjPYJV6sqJmYIdta X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.761 definitions=2021-06-10_05:2021-06-10,2021-06-10 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 priorityscore=1501 impostorscore=0 bulkscore=0 phishscore=0 adultscore=0 mlxlogscore=999 mlxscore=0 spamscore=0 lowpriorityscore=0 clxscore=1011 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2106100062 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Adding a probe can fail in a few scenarios. perf already checks for the address in the kprobe blacklist. However, the address could still be a jump label, or have a BUG_ON(). In such cases, it isn't always evident why adding the probe failed. Add a hint so that the user knows how to proceed. Reported-by: Aneesh Kumar K.V Signed-off-by: Naveen N. Rao --- tools/perf/builtin-probe.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c index 6b150756677014..ff9f3fdce600dd 100644 --- a/tools/perf/builtin-probe.c +++ b/tools/perf/builtin-probe.c @@ -352,8 +352,11 @@ static int perf_add_probe_events(struct perf_probe_event *pevs, int npevs) } ret = apply_perf_probe_events(pevs, npevs); - if (ret < 0) + if (ret < 0) { + pr_info("Hint: Check dmesg to understand reason for probe failure.\n" + " Consider probing at the next/previous instruction.\n"); goto out_cleanup; + } for (i = k = 0; i < npevs; i++) k += pevs[i].ntevs; base-commit: 0808b3d5b7514dc856178dbc509929329bbf301d -- 2.31.1