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Fri, 13 Aug 2021 06:42:35 +0000 (GMT) Subject: Re: [PATCH] hrtimer: Use raw_cpu_ptr() in clock_was_set() To: Thomas Gleixner , Mike Galbraith , linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org Cc: Peter Zijlstra , x86@kernel.org From: Marek Szyprowski Message-ID: <72282431-2d9e-048c-62c5-1fb62ebd8f5d@samsung.com> Date: Fri, 13 Aug 2021 08:42:35 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <875ywacsmb.ffs@tglx> Content-Transfer-Encoding: 7bit Content-Language: en-US X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprBKsWRmVeSWpSXmKPExsWy7djPc7oxImKJBk8um1iseXOLxeLyrjls FufPrGK3ON57gMli86apzBY/NjxmdWDz+PAxzmPzCi2PTas62TzenTvH7vF5k1wAaxSXTUpq TmZZapG+XQJXxt+N+5kKLvFWTNz8iq2BsYW7i5GTQ0LARGLH5rssXYxcHEICKxgl/uydygjh fGGUOLb1LROE85lRYuq0HmaYlpVn7kIlljNKdD+5zwzhfGSU2HXuPCtIlbCAk8Tn9f/ZQRIi At2MEqs6N7CBJJgFLCX6lmxjAbHZBAwlut52gcV5BewkZjZsAmrm4GARUJU4/cgOJCwqkCwx 8ckkVogSQYmTM5+AtXIKKEn8fdnJAjFSXmL72znMELa4xK0n88GukxC4wiFx+8RrdoizXSTW brrHAmELS7w6vgUqLiNxenIPC0RDM6PEw3Nr2SGcHkaJy00zGCGqrCXunPvFBnIds4CmxPpd +hBhR4klpx4xg4QlBPgkbrwVhDiCT2LStulQYV6JjjYhiGo1iVnH18GtPXjhEvMERqVZSF6b heSdWUjemYWwdwEjyypG8dTS4tz01GKjvNRyveLE3OLSvHS95PzcTYzAxHP63/EvOxiXv/qo d4iRiYPxEKMEB7OSCG+xsFiiEG9KYmVValF+fFFpTmrxIUZpDhYlcd6kLWvihQTSE0tSs1NT C1KLYLJMHJxSDUwWiQXNS1/cYjGMCLtd9OS7j8uKjyfizvzVD93SoWvJcfN4v3feHCY26fWX A5UqrjkI794v1ScU8y2SbfmB9i9G821aHK09y37sZTo/PZyxc+GdzuefXXf7ZM8VlmkKPrz+ R7+Re0HTO765uWKbHiyx4j+admDC1wO6lpJ176ZPTLjb18I4SVxSNcXG0k/BbE9fuXW0ovsi qa0sRz9NfjMj0DUoIKV03+vkE/du+7hrX5uSEX2w86Hime6f/yoTlU/Wy2Rkz1kud2hKkXc0 x0ZfTff9+aaNHmoxrp/Wvd548I5DuHLoAZa7HyT7J8mb3whZkOU3dY3x950TnJ0XmP+ukt58 pSHp/G3H8OMNK5RYijMSDbWYi4oTAWXlp+GrAwAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrFIsWRmVeSWpSXmKPExsVy+t/xu7oxImKJBu0XJS3WvLnFYnF51xw2 i/NnVrFbHO89wGSxedNUZosfGx6zOrB5fPgY57F5hZbHplWdbB7vzp1j9/i8SS6ANUrPpii/ tCRVISO/uMRWKdrQwkjP0NJCz8jEUs/Q2DzWyshUSd/OJiU1J7MstUjfLkEv4+/G/UwFl3gr Jm5+xdbA2MLdxcjJISFgIrHyzF2mLkYuDiGBpYwSM/7vZoVIyEicnNYAZQtL/LnWxQZR9J5R YuXJi8wgCWEBJ4nP6/+zgyREBLoZJc48ncYCkmAWsJToW7KNBaJjNZPE54df2EASbAKGEl1v u8BsXgE7iZkNm4BWcHCwCKhKnH5kBxIWFUiW+HB6KStEiaDEyZlPwGZyCihJ/H3ZCTXfTGLe 5ofMELa8xPa3c6BscYlbT+YzTWAUmoWkfRaSlllIWmYhaVnAyLKKUSS1tDg3PbfYSK84Mbe4 NC9dLzk/dxMjMNK2Hfu5ZQfjylcf9Q4xMnEwHmKU4GBWEuEtFhZLFOJNSaysSi3Kjy8qzUkt PsRoCvTORGYp0eR8YKznlcQbmhmYGpqYWRqYWpoZK4nzmhxZEy8kkJ5YkpqdmlqQWgTTx8TB KdXAxG603vKJ4/OPitLX1baszPjmFnc5zOVYvvsJsQV6uclhb4xnVqz8Z9Ltc/S2jJiMwiOT FWZX9Pf+TMxf/uhiQ/kdqyLBQu7nO/ewGdVufLJn/3G/x8HV2vvendv98My7tNypvalnrJ68 mHigcsX7oukGjf+qpkzl3vH0pvCHqXeSfbs+nJ2s5/3chZ99qnLJ7uuqmmwXn1nvnX2iXe7g TwsHh7lP953ZKdjD905sqUaSY8Jb1mn3G/ZtDZK0WP1AzYTn4odDwuIumXsX/xf+q2bUq/J5 V3EF+6Nsq7S8d9Kvtr/h/aW8pnHJxjQ3T6Yp3k/Xz9t8avemgx55pws6jWevLE49c7Ho56/f /qUFn5OUWIozEg21mIuKEwEGa8g+PQMAAA== X-CMS-MailID: 20210813064236eucas1p12488eb5bcdda32a1a0a8c80991eb1bcb X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-RootMTR: 20210812203131eucas1p22c7a4049c7f78825e80d1624dbd78805 X-EPHeader: CA CMS-TYPE: 201P X-CMS-RootMailID: 20210812203131eucas1p22c7a4049c7f78825e80d1624dbd78805 References: <20210713135158.054424875@linutronix.de> <162861133759.395.7795246170325882103.tip-bot2@tip-bot2> <7dfb3b15af67400227e7fa9e1916c8add0374ba9.camel@gmx.de> <87a6lmiwi0.ffs@tglx> <875ywacsmb.ffs@tglx> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12.08.2021 22:31, Thomas Gleixner wrote: > clock_was_set() can be invoked from preemptible context. Use raw_cpu_ptr() > to check whether high resolution mode is active or not. It does not matter > whether the task migrates after acquiring the pointer. > > Fixes: e71a4153b7c2 ("hrtimer: Force clock_was_set() handling for the HIGHRES=n, NOHZ=y case") > Reported-by: Mike Galbraith > Signed-off-by: Thomas Gleixner Tested-by: Marek Szyprowski This fixes the following issue: BUG: using smp_processor_id() in preemptible [00000000] code: hwclock/227 > --- > kernel/time/hrtimer.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > --- a/kernel/time/hrtimer.c > +++ b/kernel/time/hrtimer.c > @@ -944,10 +944,11 @@ static bool update_needs_ipi(struct hrti > */ > void clock_was_set(unsigned int bases) > { > + struct hrtimer_cpu_base *cpu_base = raw_cpu_ptr(&hrtimer_bases); > cpumask_var_t mask; > int cpu; > > - if (!hrtimer_hres_active() && !tick_nohz_active) > + if (!__hrtimer_hres_active(cpu_base) && !tick_nohz_active) > goto out_timerfd; > > if (!zalloc_cpumask_var(&mask, GFP_KERNEL)) { > @@ -958,9 +959,9 @@ void clock_was_set(unsigned int bases) > /* Avoid interrupting CPUs if possible */ > cpus_read_lock(); > for_each_online_cpu(cpu) { > - struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu); > unsigned long flags; > > + cpu_base = &per_cpu(hrtimer_bases, cpu); > raw_spin_lock_irqsave(&cpu_base->lock, flags); > > if (update_needs_ipi(cpu_base, bases)) > Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland