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[195.250.132.146]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3f00cc58b91sm18616483f8f.1.2025.09.23.09.59.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 23 Sep 2025 09:59:18 -0700 (PDT) From: =?UTF-8?q?Michal=20Koutn=C3=BD?= To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: =?UTF-8?q?Michal=20Koutn=C3=BD?= , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers Subject: [PATCH] tracing: Ensure optimized hashing works Date: Tue, 23 Sep 2025 18:59:07 +0200 Message-ID: <20250923165908.2399256-1-mkoutny@suse.com> X-Mailer: git-send-email 2.51.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable If ever PID_MAX_DEFAULT changes, it must be compatible with tracing hashmaps assumptions. Link: https://lore.kernel.org/r/20240409110126.651e94cb@gandalf.local.home/ Signed-off-by: Michal Koutn=C3=BD --- kernel/trace/trace_sched_switch.c | 2 ++ 1 file changed, 2 insertions(+) Drive-by flushing an old idea. Take it or leave it. diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_s= witch.c index cb49f7279dc80..aabae7daaac91 100644 --- a/kernel/trace/trace_sched_switch.c +++ b/kernel/trace/trace_sched_switch.c @@ -243,6 +243,8 @@ int trace_create_savedcmd(void) int trace_save_cmdline(struct task_struct *tsk) { unsigned tpid, idx; + /* so that map_pid_to_cmdline indexing is efficient */ + BUILD_BUG_ON(!is_power_of_2(PID_MAX_DEFAULT)); =20 /* treat recording of idle task as a success */ if (!tsk->pid) --=20 2.51.0