From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
x86@kernel.org, David Woodhouse <dwmw2@infradead.org>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Brian Gerst <brgerst@gmail.com>,
Arjan van de Veen <arjan@linux.intel.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Paul McKenney <paulmck@kernel.org>,
Tom Lendacky <thomas.lendacky@amd.com>,
Sean Christopherson <seanjc@google.com>,
Oleksandr Natalenko <oleksandr@natalenko.name>,
Paul Menzel <pmenzel@molgen.mpg.de>,
"Guilherme G. Piccoli" <gpiccoli@igalia.com>,
Piotr Gorski <lucjan.lucjanov@gmail.com>,
Usama Arif <usama.arif@bytedance.com>,
Juergen Gross <jgross@suse.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
xen-devel@lists.xenproject.org,
Russell King <linux@armlinux.org.uk>,
Arnd Bergmann <arnd@arndb.de>,
linux-arm-kernel@lists.infradead.org,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Guo Ren <guoren@kernel.org>,
linux-csky@vger.kernel.org,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
linux-mips@vger.kernel.org,
"James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
Helge Deller <deller@gmx.de>,
linux-parisc@vger.kernel.org,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
linux-riscv@lists.infradead.org,
Mark Rutland <mark.rutland@arm.com>,
Sabin Rapan <sabrapan@amazon.com>,
"Michael Kelley (LINUX)" <mikelley@microsoft.com>
Subject: Re: [patch v3 18/36] [patch V2 18/38] cpu/hotplug: Add CPU state tracking and synchronization
Date: Tue, 9 May 2023 13:35:48 +0200 [thread overview]
Message-ID: <20230509113548.GD38236@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20230509110722.GZ83892@hirez.programming.kicks-ass.net>
On Tue, May 09, 2023 at 01:07:23PM +0200, Peter Zijlstra wrote:
> On Mon, May 08, 2023 at 09:43:55PM +0200, Thomas Gleixner wrote:
>
> > +static inline void cpuhp_ap_update_sync_state(enum cpuhp_sync_state state)
> > +{
> > + atomic_t *st = this_cpu_ptr(&cpuhp_state.ap_sync_state);
> > + int sync = atomic_read(st);
> > +
> > + while (!atomic_try_cmpxchg(st, &sync, state));
> > +}
>
> Why isn't:
>
> atomic_set(st, state);
>
> any good?
Hmm, should at the very least be atomic_set_release(), but if you want
the full barrier then:
(void)atomic_xchg(st, state);
is the much saner way to write the above.
next prev parent reply other threads:[~2023-05-09 11:37 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-08 19:43 [patch v3 00/36] cpu/hotplug, x86: Reworked parallel CPU bringup Thomas Gleixner
2023-05-08 19:43 ` [patch v3 01/36] [patch V2 01/38] x86/smpboot: Cleanup topology_phys_to_logical_pkg()/die() Thomas Gleixner
2023-05-08 19:43 ` [patch v3 02/36] cpu/hotplug: Mark arch_disable_smp_support() and bringup_nonboot_cpus() __init Thomas Gleixner
2023-05-08 19:43 ` [patch v3 03/36] x86/smpboot: Avoid pointless delay calibration if TSC is synchronized Thomas Gleixner
2023-05-08 19:43 ` [patch v3 04/36] x86/smpboot: Rename start_cpu0() to soft_restart_cpu() Thomas Gleixner
2023-05-08 19:43 ` [patch v3 05/36] x86/topology: Remove CPU0 hotplug option Thomas Gleixner
2023-05-08 19:43 ` [patch v3 06/36] x86/smpboot: Remove the CPU0 hotplug kludge Thomas Gleixner
2023-05-08 19:43 ` [patch v3 07/36] x86/smpboot: Restrict soft_restart_cpu() to SEV Thomas Gleixner
2023-05-08 19:43 ` [patch v3 08/36] x86/smpboot: Split up native_cpu_up() into separate phases and document them Thomas Gleixner
2023-05-09 10:04 ` Peter Zijlstra
2023-05-09 12:07 ` Thomas Gleixner
2023-05-09 17:59 ` Thomas Gleixner
2023-05-09 20:11 ` Thomas Gleixner
2023-05-10 8:39 ` Peter Zijlstra
2023-05-09 10:19 ` Peter Zijlstra
2023-05-09 12:08 ` Thomas Gleixner
2023-05-09 18:03 ` Thomas Gleixner
2023-05-09 10:31 ` Peter Zijlstra
2023-05-09 12:09 ` Thomas Gleixner
2023-05-08 19:43 ` [patch v3 09/36] x86/smpboot: Get rid of cpu_init_secondary() Thomas Gleixner
2023-05-08 19:43 ` [patch v3 10/36] [patch V2 10/38] x86/cpu/cacheinfo: Remove cpu_callout_mask dependency Thomas Gleixner
2023-05-08 19:43 ` [patch v3 11/36] [patch V2 11/38] x86/smpboot: Move synchronization masks to SMP boot code Thomas Gleixner
2023-05-08 19:43 ` [patch v3 12/36] [patch V2 12/38] x86/smpboot: Make TSC synchronization function call based Thomas Gleixner
2023-05-08 19:43 ` [patch v3 13/36] x86/smpboot: Remove cpu_callin_mask Thomas Gleixner
2023-05-09 10:49 ` Peter Zijlstra
2023-05-09 12:09 ` Thomas Gleixner
2023-05-08 19:43 ` [patch v3 14/36] [patch V2 14/38] cpu/hotplug: Rework sparse_irq locking in bringup_cpu() Thomas Gleixner
2023-05-09 11:02 ` Peter Zijlstra
2023-05-09 12:10 ` Thomas Gleixner
2023-05-08 19:43 ` [patch v3 15/36] x86/smpboot: Remove wait for cpu_online() Thomas Gleixner
2023-05-08 19:43 ` [patch v3 16/36] x86/xen/smp_pv: Remove wait for CPU online Thomas Gleixner
2023-05-08 19:43 ` [patch v3 17/36] x86/xen/hvm: Get rid of DEAD_FROZEN handling Thomas Gleixner
2023-05-08 19:43 ` [patch v3 18/36] [patch V2 18/38] cpu/hotplug: Add CPU state tracking and synchronization Thomas Gleixner
2023-05-09 11:07 ` Peter Zijlstra
2023-05-09 11:35 ` Peter Zijlstra [this message]
2023-05-09 12:12 ` Thomas Gleixner
2023-05-08 19:43 ` [patch v3 19/36] x86/smpboot: Switch to hotplug core state synchronization Thomas Gleixner
2023-05-08 19:43 ` [patch v3 20/36] cpu/hotplug: Remove cpu_report_state() and related unused cruft Thomas Gleixner
2023-05-08 19:44 ` [patch v3 21/36] [patch V2 21/38] ARM: smp: Switch to hotplug core state synchronization Thomas Gleixner
2023-05-08 19:44 ` [patch v3 22/36] arm64: " Thomas Gleixner
2023-05-08 19:44 ` [patch v3 23/36] [patch V2 23/38] csky/smp: " Thomas Gleixner
2023-05-08 19:44 ` [patch v3 24/36] [patch V2 24/38] MIPS: SMP_CPS: " Thomas Gleixner
2023-05-08 19:44 ` [patch v3 25/36] parisc: " Thomas Gleixner
2023-05-08 19:44 ` [patch v3 26/36] riscv: " Thomas Gleixner
2023-05-08 19:44 ` [patch v3 27/36] cpu/hotplug: Remove unused state functions Thomas Gleixner
2023-05-08 19:44 ` [patch v3 28/36] cpu/hotplug: Reset task stack state in _cpu_up() Thomas Gleixner
2023-05-08 19:44 ` [patch v3 29/36] [patch V2 29/38] cpu/hotplug: Provide a split up CPUHP_BRINGUP mechanism Thomas Gleixner
2023-05-08 19:44 ` [patch v3 30/36] x86/smpboot: Enable split CPU startup Thomas Gleixner
2023-05-08 19:44 ` [patch v3 31/36] x86/apic: Provide cpu_primary_thread mask Thomas Gleixner
2023-05-24 20:48 ` Kirill A. Shutemov
2023-05-26 10:14 ` Thomas Gleixner
2023-05-27 13:40 ` Thomas Gleixner
2023-05-29 2:39 ` Kirill A. Shutemov
2023-05-29 19:27 ` Thomas Gleixner
2023-05-29 20:31 ` Kirill A. Shutemov
2023-05-30 0:54 ` Kirill A. Shutemov
2023-05-30 9:26 ` Thomas Gleixner
2023-05-30 10:34 ` Thomas Gleixner
2023-05-30 11:37 ` Kirill A. Shutemov
2023-05-30 12:09 ` [patch] x86/smpboot: Disable parallel bootup if cc_vendor != NONE Thomas Gleixner
2023-05-30 12:29 ` Kirill A. Shutemov
2023-05-30 16:00 ` Thomas Gleixner
2023-05-30 16:56 ` Sean Christopherson
2023-05-30 19:51 ` Thomas Gleixner
2023-05-30 20:03 ` Tom Lendacky
2023-05-30 20:39 ` Thomas Gleixner
2023-05-30 21:13 ` Tom Lendacky
2023-05-31 7:44 ` [patch] x86/smpboot: Fix the parallel bringup decision Thomas Gleixner
2023-05-31 11:07 ` Kirill A. Shutemov
2023-05-31 13:58 ` Tom Lendacky
2023-05-30 17:02 ` [patch] x86/smpboot: Disable parallel bootup if cc_vendor != NONE Kirill A. Shutemov
2023-05-30 17:31 ` Sean Christopherson
2023-05-30 9:26 ` [patch v3 31/36] x86/apic: Provide cpu_primary_thread mask Thomas Gleixner
2023-05-30 10:46 ` [patch] x86/realmode: Make stack lock work in trampoline_compat() Thomas Gleixner
2023-05-30 11:12 ` Kirill A. Shutemov
2023-06-08 23:34 ` Yunhong Jiang
2023-06-08 23:57 ` Andrew Cooper
2023-06-09 0:22 ` Yunhong Jiang
2023-06-10 19:50 ` David Laight
2023-06-10 22:51 ` 'Andrew Cooper'
2023-05-08 19:44 ` [patch v3 32/36] cpu/hotplug: Allow "parallel" bringup up to CPUHP_BP_KICK_AP_STATE Thomas Gleixner
2023-05-08 19:44 ` [patch v3 33/36] x86/apic: Save the APIC virtual base address Thomas Gleixner
2023-05-09 9:20 ` Sergey Shtylyov
2023-05-08 19:44 ` [patch v3 34/36] x86/smpboot: Implement a bit spinlock to protect the realmode stack Thomas Gleixner
2023-05-09 13:13 ` Peter Zijlstra
2023-05-09 13:47 ` Thomas Gleixner
2023-05-08 19:44 ` [patch v3 35/36] x86/smpboot: Support parallel startup of secondary CPUs Thomas Gleixner
2023-05-09 13:57 ` Peter Zijlstra
2023-05-08 19:44 ` [patch v3 36/36] x86/smpboot/64: Implement arch_cpuhp_init_parallel_bringup() and enable it Thomas Gleixner
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