From: Andrey Konovalov <andreyknvl@google.com>
To: Aleksandr Nogikh <a.nogikh@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>,
kuba@kernel.org, Johannes Berg <johannes@sipsolutions.net>,
Andrew Morton <akpm@linux-foundation.org>,
Eric Dumazet <edumazet@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
Marco Elver <elver@google.com>,
LKML <linux-kernel@vger.kernel.org>,
netdev <netdev@vger.kernel.org>,
linux-wireless@vger.kernel.org,
Aleksandr Nogikh <nogikh@google.com>
Subject: Re: [PATCH v2 1/3] kernel: make kcov_common_handle consider the current context
Date: Wed, 14 Oct 2020 18:03:58 +0200 [thread overview]
Message-ID: <CAAeHK+z6NLcwviYdGWZ4seoAr9-5Xa5ryonkU1wHOy0uAVpUKw@mail.gmail.com> (raw)
In-Reply-To: <20201009170202.103512-2-a.nogikh@gmail.com>
On Fri, Oct 9, 2020 at 7:02 PM Aleksandr Nogikh <a.nogikh@gmail.com> wrote:
>
> From: Aleksandr Nogikh <nogikh@google.com>
>
> 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 a hard IRQ context, it
> will return a handle for the interrupted process. This may lead to
> unreliable and incorrect coverage collection.
FWIW it's the same for soft IRQ context.
>
> 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. It will make the returned
> value more reliable and also will make it possible to use
> kcov_remote_handle in routines that can be called from any context.
>
> Signed-off-by: Aleksandr Nogikh <nogikh@google.com>
> ---
> v2:
> * Added this patch to the series.
> ---
> 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);
> --
> 2.28.0.1011.ga647a8990f-goog
>
Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
next prev parent reply other threads:[~2020-10-14 16:04 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-09 17:01 [PATCH v2 0/3] [PATCH v2 0/3] [PATCH v2 0/3] net, mac80211, kernel: enable KCOV remote coverage collection for 802.11 frame handling Aleksandr Nogikh
2020-10-09 17:02 ` [PATCH v2 1/3] kernel: make kcov_common_handle consider the current context Aleksandr Nogikh
2020-10-14 16:03 ` Andrey Konovalov [this message]
2020-10-09 17:02 ` [PATCH v2 2/3] net: store KCOV remote handle in sk_buff Aleksandr Nogikh
2020-10-09 17:02 ` [PATCH v2 3/3] mac80211: add KCOV remote annotations to incoming frame processing Aleksandr Nogikh
2020-10-09 17:13 ` [PATCH v2 0/3] [PATCH v2 0/3] [PATCH v2 0/3] net, mac80211, kernel: enable KCOV remote coverage collection for 802.11 frame handling Johannes Berg
2020-10-11 10:37 ` Andrey Konovalov
2020-10-11 11:09 ` Johannes Berg
2020-10-11 18:50 ` Johannes Berg
2020-10-11 18:53 ` Andrey Konovalov
2020-10-12 11:18 ` Aleksandr Nogikh
2020-10-12 11:21 ` Johannes Berg
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