From: Lukas Bulwahn <lukas.bulwahn@gmail.com>
To: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Subject: Question on commit dc7109aaa233 ("futex: Validate waiter correctly in futex_proxy_trylock_atomic()")
Date: Fri, 20 Aug 2021 13:17:42 +0200 [thread overview]
Message-ID: <CAKXUXMzqmN1dYpbYSCXWN9VwHn8+MXj3P=G09qD6=atwrcJ8WA@mail.gmail.com> (raw)
Dear Thomas,
in commit dc7109aaa233 ("futex: Validate waiter correctly in
futex_proxy_trylock_atomic()") visible on next-20210819, you add:
+ /*
+ * Ensure that this is a waiter sitting in futex_wait_requeue_pi()
+ * and waiting on the 'waitqueue' futex which is always !PI.
+ */
+ if (!top_waiter->rt_waiter || top_waiter->pi_state)
+ ret = -EINVAL;
However, ret is unconditionally reassigned later and erases any
intended effect of this assignment. This is making that assignment
above a Dead Store, which clang-analyzer correctly warns about and
which motivates me to write you an email.
Did you intend to return -EINVAL here? So:
+ if (!top_waiter->rt_waiter || top_waiter->pi_state)
+ return -EINVAL;
Best regards,
Lukas
Static analysis tools are as foolish as they are... but every dog has its day...
next reply other threads:[~2021-08-20 11:18 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-20 11:17 Lukas Bulwahn [this message]
2021-08-30 23:29 ` Question on commit dc7109aaa233 ("futex: Validate waiter correctly in futex_proxy_trylock_atomic()") Thomas Gleixner
2021-09-01 18:28 ` André Almeida
2021-09-01 19:19 ` Thomas Gleixner
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