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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43fe4cb1176sm54479709f8f.3.2026.04.23.06.06.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Apr 2026 06:06:14 -0700 (PDT) Date: Thu, 23 Apr 2026 14:06:12 +0100 From: David Laight To: Marco Elver Cc: Arnd Bergmann , Konstantin Komarov , Dmitry Vyukov , ntfs3@lists.linux.dev, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com Subject: Re: kcsan -Wmaybe-uninitialized warning in ntfs3 Message-ID: <20260423140612.46df8b78@pumpkin> In-Reply-To: References: <5da10cca-875b-418d-b54e-6be3ea32c266@app.fastmail.com> <28064669-bb57-4dab-bac5-cc1027bafaa3@app.fastmail.com> <0df31031-23d4-49cf-8643-f605561bf7fb@app.fastmail.com> <6eac698f-da35-4efc-b227-b54de5d1decb@app.fastmail.com> <49780769-461a-4a09-a7df-c34a2e839e45@app.fastmail.com> <4b36f629-9338-40e0-b114-ee37aaad9cf3@app.fastmail.com> <20260423091246.7ffa38c4@pumpkin> 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, 23 Apr 2026 13:35:09 +0200 Marco Elver wrote: > On Thu, 23 Apr 2026 at 10:12, David Laight wrote: > > On Wed, 22 Apr 2026 23:50:22 +0200 > > Marco Elver wrote: > > > > > Which means the simplest fix is probably the absolute_pointer() one. > > > > I'm not sure that using absolute_pointer() is right, it is normally used > > for special conversions in low level boot code. > > > > Here it might just be best to explicitly use (void *)(long)addr. > > That didn't work - tried, and warnings still there (GCC seems to see > through it). The only difference is the extra local - unless the '+ 0' matters. OPTIMIZE_HIDE_VAR() should work, but is annoying to use in a function call. You sort of need: #define OPTIMIZER_HIDE_VAL(x) {( \ auto _x = x; \ asm ("", "+r" (_x)); \ _x; \ )} (also useful for 'lying' to snprintf()) David > > So that leaves: > - absolute_pointer() > - __diag_ignore_all wrapper (mentioned elsewhere in thread) > > Preferences? > > Thanks, > -- Marco