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[34.78.140.88]) by smtp.gmail.com with ESMTPSA id 24sm20043967wmf.44.2020.10.26.08.09.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 26 Oct 2020 08:09:38 -0700 (PDT) From: Aleksandr Nogikh To: davem@davemloft.net, kuba@kernel.org, johannes@sipsolutions.net Cc: edumazet@google.com, andreyknvl@google.com, dvyukov@google.com, elver@google.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-wireless@vger.kernel.org, willemdebruijn.kernel@gmail.com, Aleksandr Nogikh Subject: [PATCH v3 1/3] kernel: make kcov_common_handle consider the current context Date: Mon, 26 Oct 2020 15:08:49 +0000 Message-Id: <20201026150851.528148-2-aleksandrnogikh@gmail.com> X-Mailer: git-send-email 2.29.0.rc1.297.gfa9743e501-goog In-Reply-To: <20201026150851.528148-1-aleksandrnogikh@gmail.com> References: <20201026150851.528148-1-aleksandrnogikh@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Aleksandr Nogikh kcov_common_handle is a method that is used to obtain a "default" KCOV remote handle of the current process. The handle can later be passed to kcov_remote_start in order to collect coverage for the processing that is initiated by one process, but done in another. For details see Documentation/dev-tools/kcov.rst and comments in kernel/kcov.c. Presently, if kcov_common_handle is called in an IRQ context, it will return a handle for the interrupted process. This may lead to unreliable and incorrect coverage collection. Adjust the behavior of kcov_common_handle in the following way. If it is called in a task context, return the common handle for the currently running task. Otherwise, return 0. Signed-off-by: Aleksandr Nogikh Reviewed-by: Andrey Konovalov --- kernel/kcov.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/kcov.c b/kernel/kcov.c index 6b8368be89c8..80bfe71bbe13 100644 --- a/kernel/kcov.c +++ b/kernel/kcov.c @@ -1023,6 +1023,8 @@ EXPORT_SYMBOL(kcov_remote_stop); /* See the comment before kcov_remote_start() for usage details. */ u64 kcov_common_handle(void) { + if (!in_task()) + return 0; return current->kcov_handle; } EXPORT_SYMBOL(kcov_common_handle);