| Message ID | 9144e10d7e854a0aa8a673332adec356d81a923c.1393576981.git.viresh.kumar@linaro.org |
|---|---|
| State | New |
| Headers | show |
> On 28-Feb-2014, at 4:22 pm, Thomas Gleixner <tglx@linutronix.de> wrote: > >> On Fri, 28 Feb 2014, Viresh Kumar wrote: >> >> Currently we are using two lowest bit of base for internal purpose and so they >> both should be zero in the allocated address. The code was doing the right thing >> before this patch came in: >> >> commit c5f66e99b7cb091e3d51ae8e8156892e8feb7fa3 >> Author: Tejun Heo <tj@kernel.org> >> Date: Wed Aug 8 11:10:28 2012 -0700 >> >> timer: Implement TIMER_IRQSAFE >> >> Tejun probably forgot to update this piece of code which checks if the lowest >> 'n' bits are zero or not and so wasn't updated according to the new flag. Lets >> use TIMER_FLAG_MASK in the calculations here, so that this code wouldn't require >> a change later on with another flag in. > > Are you planning to introduce more flag horror? Don't go there. The > timer_list code is about to be rewritten completely and I'm not going > to add new features to the existing code base. Not at all. I was just trying to understand this framework and found this Issue.-- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Hi Thomas, On 28 February 2014 18:52, Thomas Gleixner <tglx@linutronix.de> wrote: > On Fri, 28 Feb 2014, Viresh Kumar wrote: > >> Currently we are using two lowest bit of base for internal purpose and so they >> both should be zero in the allocated address. The code was doing the right thing >> before this patch came in: >> >> commit c5f66e99b7cb091e3d51ae8e8156892e8feb7fa3 >> Author: Tejun Heo <tj@kernel.org> >> Date: Wed Aug 8 11:10:28 2012 -0700 >> >> timer: Implement TIMER_IRQSAFE >> >> Tejun probably forgot to update this piece of code which checks if the lowest >> 'n' bits are zero or not and so wasn't updated according to the new flag. Lets >> use TIMER_FLAG_MASK in the calculations here, so that this code wouldn't require >> a change later on with another flag in. > > Are you planning to introduce more flag horror? Don't go there. The > timer_list code is about to be rewritten completely and I'm not going > to add new features to the existing code base. Do you already have stuff prepared that can be shared on that? I am asking because I am working on some CPU isolation stuff for Networking domain and it looks like I need to add another of these flags :( .. I know its just not acceptable and so wanted your thoughts on how can I get things fixed. Peter asked me to implement something like cpuset.quiesce to move away all timers/workqueues/etc from a cpuset. It was proposed here: https://lkml.org/lkml/2014/1/15/186 Now, I was looking to migrate away the timers first but I obviously shouldn't migrate the pinned timers. One way out to identify PINNED timers is to mark them PINNED with the flag bits, which you wouldn't allow. Can you give some other idea with which I can get this solved. -- viresh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
On 11 March 2014 15:56, Viresh Kumar <viresh.kumar@linaro.org> wrote: > Hi Thomas, > > On 28 February 2014 18:52, Thomas Gleixner <tglx@linutronix.de> wrote: >> On Fri, 28 Feb 2014, Viresh Kumar wrote: >> >>> Currently we are using two lowest bit of base for internal purpose and so they >>> both should be zero in the allocated address. The code was doing the right thing >>> before this patch came in: >>> >>> commit c5f66e99b7cb091e3d51ae8e8156892e8feb7fa3 >>> Author: Tejun Heo <tj@kernel.org> >>> Date: Wed Aug 8 11:10:28 2012 -0700 >>> >>> timer: Implement TIMER_IRQSAFE >>> >>> Tejun probably forgot to update this piece of code which checks if the lowest >>> 'n' bits are zero or not and so wasn't updated according to the new flag. Lets >>> use TIMER_FLAG_MASK in the calculations here, so that this code wouldn't require >>> a change later on with another flag in. >> >> Are you planning to introduce more flag horror? Don't go there. The >> timer_list code is about to be rewritten completely and I'm not going >> to add new features to the existing code base. > > Do you already have stuff prepared that can be shared on that? I am asking > because I am working on some CPU isolation stuff for Networking domain and > it looks like I need to add another of these flags :( .. I know its > just not acceptable > and so wanted your thoughts on how can I get things fixed. > > Peter asked me to implement something like cpuset.quiesce to move away all > timers/workqueues/etc from a cpuset. It was proposed here: > > https://lkml.org/lkml/2014/1/15/186 > > Now, I was looking to migrate away the timers first but I obviously > shouldn't migrate > the pinned timers. One way out to identify PINNED timers is to mark them PINNED > with the flag bits, which you wouldn't allow. Can you give some other idea with > which I can get this solved. Ping!! -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
On Tue, 18 Mar 2014, Viresh Kumar wrote: > On 11 March 2014 15:56, Viresh Kumar <viresh.kumar@linaro.org> wrote: > > > > Now, I was looking to migrate away the timers first but I > > obviously shouldn't migrate the pinned timers. One way out to > > identify PINNED timers is to mark them PINNED with the flag bits, > > which you wouldn't allow. Can you give some other idea with which > > I can get this solved. Sigh, I really hoped to find some time to finish the rework, but then you get to debug bugs, solve the problem and are rewarded with a full inbox. Lather, rinse, repeat... Go ahead and make the timer base aligned with more room for some bits to tweak. The new stuff will have a flags field where stuff like pinned is stored. Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
diff --git a/kernel/timer.c b/kernel/timer.c index e8e7839..d52a8ff 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -1548,9 +1548,8 @@ static int init_timers_cpu(int cpu) if (!base) return -ENOMEM; - /* Make sure that tvec_base is 2 byte aligned */ - if (tbase_get_deferrable(base)) { - WARN_ON(1); + /* Make sure tvec_base has TIMER_FLAG_MASK bits free */ + if (WARN_ON(base != tbase_get_base(base))) { kfree(base); return -ENOMEM; }
Currently we are using two lowest bit of base for internal purpose and so they both should be zero in the allocated address. The code was doing the right thing before this patch came in: commit c5f66e99b7cb091e3d51ae8e8156892e8feb7fa3 Author: Tejun Heo <tj@kernel.org> Date: Wed Aug 8 11:10:28 2012 -0700 timer: Implement TIMER_IRQSAFE Tejun probably forgot to update this piece of code which checks if the lowest 'n' bits are zero or not and so wasn't updated according to the new flag. Lets use TIMER_FLAG_MASK in the calculations here, so that this code wouldn't require a change later on with another flag in. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> --- kernel/timer.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)