linux-kernel - Re: [RFC][PATCH v2 00/31] timers: Use del_timer

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Date:   Fri, 28 Oct 2022 21:57:14 +0000
From:   Trond Myklebust <trondmy@...merspace.com>
To:     Steven Rostedt <rostedt@...dmis.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Stephen Boyd <sboyd@...nel.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Anna Schumaker <anna@...nel.org>,
        "linux-nfs@...r.kernel.org" <linux-nfs@...r.kernel.org>
Subject: Re: [RFC][PATCH v2 00/31] timers: Use del_timer_shutdown() before
 freeing timers



> On Oct 28, 2022, at 16:49, Steven Rostedt <rostedt@...dmis.org> wrote:
> 
> On Fri, 28 Oct 2022 20:12:30 +0000
> Trond Myklebust <trondmy@...merspace.com> wrote:
> 
>> I seem to vaguely remember that at the time, del_timer_sync() would loop
>> in order to catch re-arming timers, whereas del_singleshot_timer_sync()
>> would not, hence the commit message. The expectation for
>> del_singleshot_timer_sync() was simply that the caller would ensure
>> safety against re-arming, which was indeed the case for this code.
> 
> Well, that expectation didn't last long. Your commit was added on June 22,
> 2005. Then on June 23, 2005 (the next day!) this happened:
> 
> 
> 55c888d6d09a0 ("timers fixes/improvements")
> 
> Which has:
> 
> @@ -89,12 +77,12 @@ static inline void add_timer(struct timer_list * timer)
> 
> #ifdef CONFIG_SMP
>   extern int del_timer_sync(struct timer_list *timer);
> -  extern int del_singleshot_timer_sync(struct timer_list *timer);
> #else
> # define del_timer_sync(t) del_timer(t)
> -# define del_singleshot_timer_sync(t) del_timer(t)
> #endif
> 
> +#define del_singleshot_timer_sync(t) del_timer_sync(t)
> +
> 
> 
> So much or efficiency! :-)
> 
> I guess converting it back to del_timer_sync() is the right thing to do
> regardless of this patch series. I'll send you a patch.
> 
> -- Steve

We’re all moving a lot slower now, 17 years later...

_________________________________
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@...merspace.com