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[83.149.199.196]) by smtp.gmail.com with ESMTPSA id b40sm525355edc.53.2019.08.28.08.36.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 28 Aug 2019 08:36:54 -0700 (PDT) Reply-To: efremov@linux.com Subject: Re: [PATCH v2] checkpatch: check for nested unlikely calls To: Andy Whitcroft , Joe Perches Cc: Andrew Morton , linux-kernel@vger.kernel.org References: <20190827165515.21668-1-efremov@linux.com> <20190828133256.13630-1-efremov@linux.com> From: Denis Efremov Message-ID: <9655ddea-a98d-073c-f130-e9345517f44f@linux.com> Date: Wed, 28 Aug 2019 18:36:53 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190828133256.13630-1-efremov@linux.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/28/19 4:32 PM, Denis Efremov wrote: > IS_ERR, IS_ERR_OR_NULL, IS_ERR_VALUE already contain unlikely optimization > internally. Thus, there is no point in calling these functions under > likely/unlikely. It looks like this rule could be extended with this list: CHECK_DATA_CORRUPTION GLOCK_BUG_ON SPIN_BUG_ON RWLOCK_BUG_ON DCCP_BUG_ON GEM_BUG_ON BUG_ON WARN WARN_TAINT WARN_ON_ONCE WARN_ONCE WARN_TAINT_ONCE WARN_ON_SMP However, grep shows that maybe only BUG_ON, WARN_ON, WARN, WARN_ON_ONCE worth checking: git grep 'likely(\s*\(CHECK_DATA_CORRUPTION\|GLOCK_BUG_ON\|SPIN_BUG_ON\|RWLOCK_BUG_ON\|DCCP_BUG_ON\|GEM_BUG_ON\|BUG_ON\|WARN\|WARN_TAINT\|WARN_ON_ONCE\|WARN_ONCE\|WARN_TAINT_ONCE\|WARN_ON_SMP\)' . drivers/gpu/drm/msm/disp/mdp5/mdp5_ctl.c: if (unlikely(WARN_ON(!mixer))) { drivers/gpu/drm/msm/disp/mdp5/mdp5_ctl.c: if (unlikely(WARN_ON(ctl_cfg->count > MAX_CTL))) { drivers/gpu/drm/msm/disp/mdp_format.c: if (unlikely(WARN_ON(type >= CSC_MAX))) drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_tx.c: if (unlikely(WARN_ON_ONCE(tls_ctx->netdev != netdev))) drivers/net/wimax/i2400m/tx.c: if (unlikely(WARN_ON(pad_buf == NULL drivers/xen/events/events_base.c: if (unlikely(WARN(irq >= nr_irqs, "Invalid irq %d!\n", irq))) fs/open.c: if (unlikely(WARN_ON(!f->f_op))) { fs/xfs/xfs_buf.c: if (unlikely(WARN_ON(!bp->b_ops || !bp->b_ops->magic[idx]))) fs/xfs/xfs_buf.c: if (unlikely(WARN_ON(!bp->b_ops || !bp->b_ops->magic16[idx]))) > +# nested likely/unlikely calls if ($line =~ /\b(?:(?:un)?likely)\s*\(\s*!?\s*((?:IS_ERR(?:_OR_NULL|_VALUE)?)|(?:BUG_ON|WARN(?:_ON(?:_ONCE)?)?)))/) { or maybe even to match all possible WARNs: if ($line =~ /\b(?:(?:un)?likely)\s*\(\s*!?\s*((?:IS_ERR(?:_OR_NULL|_VALUE)?)|(?:BUG_ON|WARN)))/) { > + WARN("LIKELY_MISUSE", > + "nested (un)?likely calls, unlikely already used in $1 internally\n" . $herecurr); > + } Any suggestions for v3? Thanks, Denis