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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-435b1c24bedsm24336005f8f.17.2026.01.25.14.38.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 25 Jan 2026 14:38:13 -0800 (PST) Date: Sun, 25 Jan 2026 22:38:12 +0000 From: David Laight To: David Yang Cc: netdev@vger.kernel.org, Lorenzo Bianconi , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next v2 1/2] u64_stats: Allow u64_stats_add() to accept s64 Message-ID: <20260125223812.3a2ae148@pumpkin> In-Reply-To: <20260125220753.3984326-2-mmyangfl@gmail.com> References: <20260125220753.3984326-1-mmyangfl@gmail.com> <20260125220753.3984326-2-mmyangfl@gmail.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260125_143816_160439_A8B1FC4B X-CRM114-Status: GOOD ( 18.97 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, 26 Jan 2026 06:07:49 +0800 David Yang wrote: > The current u64_stats_add() accepts only unsigned long, which makes no > sense as u64_stats_set() accepts u64 already, and causes unnecessary > narrowing on 32-bit architectures. Isn't is a chicken/egg? A value over 2^31 could just be a very large value that needs to be added. Where the add is being done 'just in time' so avoid overflow. David > > Moreover, since there's no u64_stats_sub(), users may be tempted to > reuse it for decrements, which already happened on nft_counter_reset() > in net/netfilter/nft_counter.c . > > Change to s64 to allow both positive and negative values. > > Signed-off-by: David Yang > --- > include/linux/u64_stats_sync.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/include/linux/u64_stats_sync.h b/include/linux/u64_stats_sync.h > index 457879938fc1..e77f2b30bac7 100644 > --- a/include/linux/u64_stats_sync.h > +++ b/include/linux/u64_stats_sync.h > @@ -84,7 +84,7 @@ static inline void u64_stats_set(u64_stats_t *p, u64 val) > local64_set(&p->v, val); > } > > -static inline void u64_stats_add(u64_stats_t *p, unsigned long val) > +static inline void u64_stats_add(u64_stats_t *p, s64 val) > { > local64_add(val, &p->v); > } > @@ -125,7 +125,7 @@ static inline void u64_stats_set(u64_stats_t *p, u64 val) > p->v = val; > } > > -static inline void u64_stats_add(u64_stats_t *p, unsigned long val) > +static inline void u64_stats_add(u64_stats_t *p, s64 val) > { > p->v += val; > }