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From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>, Ingo Molnar <mingo@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	John Stultz <john.stultz@linaro.org>,
	Frederic Weisbecker <frederic@kernel.org>,
	Anna-Maria Behnsen <anna-maria@linutronix.de>,
	Christoph Hellwig <hch@lst.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jiri Slaby <jslaby@suse.com>
Subject: [patch V2 31/38] rlimit: Rewrite non-sensical RLIMIT_CPU comment
Date: Wed, 21 Aug 2019 21:09:18 +0200
Message-ID: <20190821192922.185511287@linutronix.de> (raw)
In-Reply-To: <20190821190847.665673890@linutronix.de>

The comment above the function which arms RLIMIT_CPU in the posix CPU timer
code makes no sense at all. It claims that the kernel does not return an
error code when it rejected the attempt to set RLIMIT_CPU. That's clearly
bogus as the code does an error check and the rlimit is only set and
activated when the permission checks are ok. In case of a rejection an
appropriate error code is returned.

This is a historical and outdated comment which got dragged along even when
the rlimit handling code was rewritten.

Replace it with an explanation why the setup function is not called when
the rlimit value is RLIM_INFINITY and how the 'disarming' is handled.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
---
 kernel/sys.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1576,10 +1576,9 @@ int do_prlimit(struct task_struct *tsk,
 	task_unlock(tsk->group_leader);
 
 	/*
-	 * RLIMIT_CPU handling.   Note that the kernel fails to return an error
-	 * code if it rejected the user's attempt to set RLIMIT_CPU.  This is a
-	 * very long-standing error, and fixing it now risks breakage of
-	 * applications, so we live with it
+	 * RLIMIT_CPU handling. Arm the posix CPU timer if the limit is not
+	 * infite. In case of RLIM_INFINITY the posix CPU timer code
+	 * ignores the rlimit.
 	 */
 	 if (!retval && new_rlim && resource == RLIMIT_CPU &&
 	     new_rlim->rlim_cur != RLIM_INFINITY &&



  parent reply index

Thread overview: 137+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-21 19:08 [patch V2 00/38] posix-cpu-timers: Cleanup and consolidation Thomas Gleixner
2019-08-21 19:08 ` [patch V2 01/38] posix-cpu-timers: Provide task validation functions Thomas Gleixner
2019-08-21 22:33   ` Frederic Weisbecker
2019-08-21 23:03     ` Frederic Weisbecker
2019-08-23 15:33       ` Thomas Gleixner
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:08 ` [patch V2 02/38] posix-cpu-timers: Use common permission check in posix_cpu_clock_get() Thomas Gleixner
2019-08-21 23:40   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-29 11:00     ` kbuild test robot
2019-08-29 11:21       ` Thomas Gleixner
2019-08-30  1:08         ` [kbuild-all] " Philip Li
2019-08-29 11:23     ` kbuild test robot
2019-08-21 19:08 ` [patch V2 03/38] posix-cpu-timers: Use common permission check in posix_cpu_timer_create() Thomas Gleixner
2019-08-21 23:49   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:08 ` [patch V2 04/38] posix-cpu-timers: Provide quick sample function for itimer Thomas Gleixner
2019-08-22 12:13   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:08 ` [patch V2 05/38] itimers: Use quick sample function Thomas Gleixner
2019-08-22 12:15   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-29 23:47     ` kbuild test robot
2019-08-30  6:01       ` Thomas Gleixner
2019-08-21 19:08 ` [patch V2 06/38] posix-cpu-timers: Sample directly in timer check Thomas Gleixner
2019-08-22 12:30   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:08 ` [patch V2 07/38] posix-cpu-timers: Rename thread_group_cputimer() and make it static Thomas Gleixner
2019-08-22 12:41   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:08 ` [patch V2 08/38] posix-cpu-timers: Consolidate thread group sample code Thomas Gleixner
2019-08-22 13:49   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:08 ` [patch V2 09/38] posix-cpu-timers: Use clock ID in posix_cpu_timer_set() Thomas Gleixner
2019-08-22 13:58   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:08 ` [patch V2 10/38] posix-cpu-timers: Use clock ID in posix_cpu_timer_get() Thomas Gleixner
2019-08-22 14:07   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:08 ` [patch V2 11/38] posix-cpu-timers: Use clock ID in posix_cpu_timer_rearm() Thomas Gleixner
2019-08-22 14:12   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:08 ` [patch V2 12/38] posix-cpu-timers: Remove pointless return value check Thomas Gleixner
2019-08-22 14:15   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:09 ` [patch V2 13/38] posix-cpu-timers: Simplify sample functions Thomas Gleixner
2019-08-22 14:20   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:09 ` [patch V2 14/38] posix-cpu-timers: Get rid of pointer indirection Thomas Gleixner
2019-08-22 14:41   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:09 ` [patch V2 15/38] posix-cpu-timers: Sample task times once in expiry check Thomas Gleixner
2019-08-22 15:00   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:09 ` [patch V2 16/38] posix-cpu-timers: Move prof/virt_ticks into caller Thomas Gleixner
2019-08-22 15:05   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:09 ` [patch V2 17/38] posix-cpu-timers: Create a container struct Thomas Gleixner
2019-08-22 15:32   ` Frederic Weisbecker
2019-08-23 15:34     ` Thomas Gleixner
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:09 ` [patch V2 19/38] posix-cpu-timers: Move expiry cache into struct posix_cputimers Thomas Gleixner
2019-08-22 16:29   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:09 ` [patch V2 20/38] posix-cpu-timers: Provide array based access to expiry cache Thomas Gleixner
2019-08-23 17:33   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:09 ` [patch V2 21/38] posix-cpu-timers: Simplify timer queueing Thomas Gleixner
2019-08-23 17:51   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:09 ` [patch V2 22/38] posix-cpu-timers: Simplify set_process_cpu_timer() Thomas Gleixner
2019-08-23 18:00   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:09 ` [patch V2 23/38] posix-cpu-timers: Switch check_*_timers() to array cache Thomas Gleixner
2019-08-23 18:13   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:09 ` [patch V2 24/38] posix-cpu-timers: Remove the odd field rename defines Thomas Gleixner
2019-08-23 18:36   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:09 ` [patch V2 25/38] posix-cpu-timers: Provide array based sample functions Thomas Gleixner
2019-08-23 22:08   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:09 ` [patch V2 26/38] posix-cpu-timers: Make expiry checks array based Thomas Gleixner
2019-08-23 22:44   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:09 ` [patch V2 27/38] posix-cpu-timers: Remove cputime_expires Thomas Gleixner
2019-08-23 22:50   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:09 ` [patch V2 28/38] posix-cpu-timers: Restructure expiry array Thomas Gleixner
2019-08-26 16:32   ` Frederic Weisbecker
2019-08-26 18:16     ` Thomas Gleixner
2019-08-26 18:22       ` [patch V3 " Thomas Gleixner
2019-08-26 19:45         ` Frederic Weisbecker
2019-08-28 10:16         ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-26 21:06   ` [patch V2 28/38] " Frederic Weisbecker
2019-08-26 21:46     ` Thomas Gleixner
2019-08-21 19:09 ` [patch V2 29/38] posix-cpu-timers: Switch thread group sampling to array Thomas Gleixner
2019-08-26 21:12   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:09 ` [patch V2 30/38] posix-cpu-timers: Respect INFINITY for hard RTTIME limit Thomas Gleixner
2019-08-26 21:19   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:09 ` Thomas Gleixner [this message]
2019-08-26 21:41   ` [patch V2 31/38] rlimit: Rewrite non-sensical RLIMIT_CPU comment Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:09 ` [patch V2 32/38] posix-cpu-timers: Get rid of zero checks Thomas Gleixner
2019-08-26 21:57   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:09 ` [patch V2 33/38] posix-cpu-timers: Consolidate timer expiry further Thomas Gleixner
2019-08-26 22:29   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:09 ` [patch V2 34/38] posix-cpu-timers: Get rid of 64bit divisions Thomas Gleixner
2019-08-26 22:51   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:09 ` [patch V2 35/38] posix-cpu-timers: Remove pointless comparisons Thomas Gleixner
2019-08-26 22:59   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:09 ` [patch V2 36/38] posix-cpu-timers: Deduplicate rlimit handling Thomas Gleixner
2019-08-26 23:13   ` Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:09 ` [patch V2 37/38] posix-cpu-timers: Move state tracking to struct posix_cputimers Thomas Gleixner
2019-08-26 23:28   ` Frederic Weisbecker
2019-08-26 23:33     ` Thomas Gleixner
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-21 19:09 ` [patch V2 38/38] posix-cpu-timers: Utilize timerqueue for storage Thomas Gleixner
2019-08-27  0:48   ` Frederic Weisbecker
2019-08-27  6:08     ` Thomas Gleixner
2019-08-27 13:17       ` Frederic Weisbecker
2019-08-27 13:46         ` Thomas Gleixner
2019-08-27 19:31           ` [patch V3 " Thomas Gleixner
2019-08-27 22:23             ` Frederic Weisbecker
2019-08-28 10:16             ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-08-22  0:54 ` [patch V2 00/38] posix-cpu-timers: Cleanup and consolidation Christoph Hellwig
2019-08-22  1:02   ` Frederic Weisbecker
2019-08-22  1:02     ` Christoph Hellwig
     [not found] ` <20190821192920.909530418@linutronix.de>
2019-08-22 16:06   ` [patch V2 18/38] sched: Move struct task_cputime to types.h Frederic Weisbecker
2019-08-28 10:16   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner

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