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From: Lukas Bulwahn <>
To: Thomas Gleixner <>, Ingo Molnar <>
Cc: Peter Zijlstra <>,
	LKML <>,
	Sudip Mukherjee <>
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: <> (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,


Static analysis tools are as foolish as they are... but every dog has its day...

             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 ` Thomas Gleixner
2021-09-01 18:28   ` André Almeida
2021-09-01 19:19     ` Thomas Gleixner

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