From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ej1-f67.google.com (mail-ej1-f67.google.com [209.85.218.67]) by mx.groups.io with SMTP id smtpd.web09.7055.1604634020317183499 for ; Thu, 05 Nov 2020 19:40:20 -0800 Authentication-Results: mx.groups.io; dkim=pass header.i=@gmail.com header.s=20161025 header.b=G2sPbaKV; spf=pass (domain: gmail.com, ip: 209.85.218.67, mailfrom: lukas.bulwahn@gmail.com) Received: by mail-ej1-f67.google.com with SMTP id k3so5698891ejj.10 for ; Thu, 05 Nov 2020 19:40:20 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=v31c+3qUzm/Jl9mhtRELjufMUcxhfj6Qpk0Egg0rkIc=; b=G2sPbaKVWlctWWt9dQqnUUZ26kWvTx4lqpzkKvDn9D1DxhleQxkvLOaOHnbPnk3raT Lk7PdtiqqtRFkDpPM2JXWduU85jDrg8SZreWZlATMqd6zdcLaz9YfcKnq7bEGGA+m9cX 8Oz+j9tVEk9imS/i1TzoJ0qXuejfUX/yDNMCKzUwGWr58yJWgUTUfe9hp5NueEa+RI+Y 6gaq/n+nbQqqV2c7zT3zd3ZZmmU9CYkeTmw9KfZYMsomje/mKrNiMdHr/4c3Kgl4RCWC bzLptOP6jsqvjY2KAAtprDXXZqNIVxX7p8Mpl0josoGZXcroSDGO+j5lCF40P9Qmte1l qniQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=v31c+3qUzm/Jl9mhtRELjufMUcxhfj6Qpk0Egg0rkIc=; b=Q3fB/19Nqxk/6Ri+R3yZSBeAjRYhfBAWxRJOwK2+o0FPVMLYXQlh/DQ+Tr7pAjw4rY ybPZN5sT6ry+LlSK/2C2Gv2ktu9a9A89EqZJNm+HdqAMxqDRPIzT2cqkDd8qN9H/XKYy zR3I8nKz2RwsRpVbHiN/cI+VuUUFMN1O8+Emw55l6vt+lAeXBCLbHw54fJAdhVIp5kdZ L3SyR90v13sx77vCFNCtHgFTMz7kR7+5wb8xEmKQm/U+c9VsS6OyDhxXKYTQVyBnfEQz oojCpkbpfeD48mIA88i8slSMoQP0WXTPtrSrZZZjFgmCWPoRKETdVvwNXOXLDaUPoIAS m1Ww== X-Gm-Message-State: AOAM5338i8GKSg2sPz1rdsNSaH2cY/cj4TJFqHPXhBMbHJ9PwDuhDxaf k31ls0FwRxl8qBFgP9omryU= X-Google-Smtp-Source: ABdhPJxdlgrDr75OUdeerY4h/FD+9Z7XvLQL8XO5mZ2NUVm/pGUpKmrXgCq2czkobGG4KNQiERvrOA== X-Received: by 2002:a17:906:6a57:: with SMTP id n23mr55277ejs.315.1604634018857; Thu, 05 Nov 2020 19:40:18 -0800 (PST) Return-Path: Received: from felia.fritz.box ([2001:16b8:2d20:9d00:b87b:b644:61a3:6870]) by smtp.gmail.com with ESMTPSA id z23sm2103337ejb.4.2020.11.05.19.40.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Nov 2020 19:40:18 -0800 (PST) From: "Lukas Bulwahn" To: Petr Mladek , Sergey Senozhatsky , Steven Rostedt , John Ogness Cc: Nathan Chancellor , Nick Desaulniers , linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com, kernel-janitors@vger.kernel.org, linux-safety@lists.elisa.tech, Lukas Bulwahn Subject: [PATCH] printk: remove unneeded dead-store assignment Date: Fri, 6 Nov 2020 04:40:05 +0100 Message-Id: <20201106034005.18822-1-lukas.bulwahn@gmail.com> X-Mailer: git-send-email 2.17.1 make clang-analyzer on x86_64 defconfig caught my attention with: kernel/printk/printk_ringbuffer.c:885:3: warning: Value stored to 'desc' is never read [clang-analyzer-deadcode.DeadStores] desc = to_desc(desc_ring, head_id); ^ Commit b6cf8b3f3312 ("printk: add lockless ringbuffer") introduced desc_reserve() with this unneeded dead-store assignment. As discussed with John Ogness privately, this is probably just some minor left-over from previous iterations of the ringbuffer implementation. So, simply remove this unneeded dead assignment to make clang-analyzer happy. As compilers will detect this unneeded assignment and optimize this anyway, the resulting object code is identical before and after this change. No functional change. No change to object code. Signed-off-by: Lukas Bulwahn --- applies cleanly on current master and next-20201105 John, please ack. Petr, please pick this minor non-urgent clean-up patch. kernel/printk/printk_ringbuffer.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/kernel/printk/printk_ringbuffer.c b/kernel/printk/printk_ringbuffer.c index 6b1525685277..74e25a1704f2 100644 --- a/kernel/printk/printk_ringbuffer.c +++ b/kernel/printk/printk_ringbuffer.c @@ -882,8 +882,6 @@ static bool desc_reserve(struct printk_ringbuffer *rb, unsigned long *id_out) head_id = atomic_long_read(&desc_ring->head_id); /* LMM(desc_reserve:A) */ do { - desc = to_desc(desc_ring, head_id); - id = DESC_ID(head_id + 1); id_prev_wrap = DESC_ID_PREV_WRAP(desc_ring, id); -- 2.17.1