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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49b91728319sm46252715e9.12.2026.08.28.01.22.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 28 Aug 2026 01:22:07 -0700 (PDT) Date: Fri, 28 Aug 2026 09:22:05 +0100 From: David Laight To: Boqun Feng Cc: Thomas Gleixner , Peter Zijlstra , linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH] locking: Revert switching guards to _irq_{disable,enable}() Message-ID: <20260828092205.2e65e299@pumpkin> In-Reply-To: References: <20260804161447.84806-8-boqun@kernel.org> <178635226387.442315.3868294476114711805.tip-bot2@tip-bot2> <20260824104704.GA4121339@noisy.programming.kicks-ass.net> <20260824105523.GA4121620@noisy.programming.kicks-ass.net> <877bldhkmq.ffs@fw13> <87v78wezid.ffs@fw13> <875x0vfgtl.ffs@fw13> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 27 Aug 2026 14:33:05 -0700 Boqun Feng wrote: .... > Yes, if we go to the level to unify all irq disabling with counter > tracking then I think using arch_local_irq_disable() is possible and > makes a lot of senses. Where are you thinking of keeping the counter? On non-x86 accessing it may be expensive. The best bet is probably in 'current'. Doesn't that make this valid? int c = current->irq_disable_count; if (c) { current->irq_disable_count = c + 1; return c; } disable_irq(); // asm("cli") interrupt_disable_barrier(); // ISTR arm needs this current->irq_disable_count = 1; return 0; } The task can be preempted in the middle - but that doesn't matter. If spin_lock_irqsave() returns current->irq_disable_count then any existing code that does lock chaining works unaltered. David > > Regards, > Boqun > > > Thanks, > > > > tglx > > >