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.web12.35782.1601297107822227602 for ; Mon, 28 Sep 2020 05:45:08 -0700 Authentication-Results: mx.groups.io; dkim=pass header.i=@gmail.com header.s=20161025 header.b=uCS0qWvu; 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 r7so8261555ejs.11 for ; Mon, 28 Sep 2020 05:45:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=eDbNGoXjUOxyTq/2/7gQ4AH74xLZ8mTu0ngi+MaAE+k=; b=uCS0qWvuD09wigPlBYfAAAyoZyfjUT2Xc99XxqOxnCIlYvflGWoHp0ftk6mZH5d/uT 3Q5APB8NEVGPO20LVhDzCsYjZACyTTRbVfXtTp9ttdpHA+8P+WIwl0wBdAQXlumqmfid prEWKXdYRBu6R2rDyNiN+EM4Whl6dk3xbOhxSvs2rmI2rzxjo1EbwIWjgPhmmwS0SDhz NjYspqFgLLmxjrijp5cYue/6BehuzCNHBInqzGbbw46DaPO+BPYv6kotgwRBQPGQ8uFw I7YROKBUhceRMTsDZHCKtWzjjmQ8/Rcz8scWhZCYqgg01BbE8tCpTZ0J217sajEvMiUt 8DDQ== 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=eDbNGoXjUOxyTq/2/7gQ4AH74xLZ8mTu0ngi+MaAE+k=; b=etsxsrnOJNVFqJjdMljlY4ceRzN85bW7K+fMrrSVZ6DBG2AUBj0dgNG3El5zteK1fl AIAFzar/HTLIalpib+7iker2zeOq+00D+n7Zj/JTdAcpl2/aNAhMtNwxjKoO1aWpC7R/ PbUHIwBssZdHdl6NXks7sYFHf2j8UH92m7xroLaj67SxlIf9GY1Rk3tmYz3AFaz1TQ7m ljQ7NEs4FSeDjPeYJXJNXC3dUC1BxBH6uubzcSMoFnrkOJiY+nj8pxqx+SpJoBmxfO0R qi+Yg3yndw06W2pj54x6h8xugqzIQV02oLQeLiq50WNXHFB5eM3dWTErAX0huMI4G+Q5 nEqQ== X-Gm-Message-State: AOAM53187DUiA2XGmsjAMLhy/GVg+i2KJUS3CSo/bqfV4zxnwDfcf6tM nrzCeYW8+Wq8Oh+Ff/4f53Y= X-Google-Smtp-Source: ABdhPJwrcAeGcgwC0x4c6zDkB9w6jAFa372e6W6yiAT/BrBcUqZaC6/RpiOAZ9gQGwQKzlOFDOyv0w== X-Received: by 2002:a17:906:1192:: with SMTP id n18mr1527579eja.515.1601297106102; Mon, 28 Sep 2020 05:45:06 -0700 (PDT) Return-Path: Received: from felia.fritz.box ([2001:16b8:2d9d:5000:7872:7299:adfa:b749]) by smtp.gmail.com with ESMTPSA id m4sm1589214ede.70.2020.09.28.05.45.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Sep 2020 05:45:05 -0700 (PDT) From: "Lukas Bulwahn" To: Balbir Singh , Thomas Gleixner Cc: Dave Hansen , Andy Lutomirski , Peter Zijlstra , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , 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 -next for tip:x86/pti] x86/tlb: drop unneeded local vars in enable_l1d_flush_for_task() Date: Mon, 28 Sep 2020 14:44:57 +0200 Message-Id: <20200928124457.27289-1-lukas.bulwahn@gmail.com> X-Mailer: git-send-email 2.17.1 Commit b6724f118d44 ("prctl: Hook L1D flushing in via prctl") checks the validity for enable_l1d_flush_for_task() and introduces some superfluous local variables for that implementation. make clang-analyzer on x86_64 tinyconfig caught my attention with: arch/x86/mm/tlb.c:332:2: warning: Value stored to 'cpu' is never read \ [clang-analyzer-deadcode.DeadStores] Compilers will detect these superfluous local variables and assignment and optimize this anyway. So, the resulting binary is identical before and after this change. Simplify the code and remove superfluous local variables to make clang-analyzer happy. No functional change. No change in binary with supported compilers. Signed-off-by: Lukas Bulwahn --- applies cleanly on next-20200925 Balbir, please review and ack. Thomas, please pick this minor non-urgent clean-up patch into the x86/pti branch of tip as follow-up to: https://lore.kernel.org/lkml/160026187842.15536.285514864386042510.tip-bot2@tip-bot2/ I quickly confirmed that the binary did not change with this change to the source code; The hash of tlb.o remained the same before and after the change. So, in my setup: md5sum tlb.o 7c7e096bab0fd87bd2c8437d8c7dc3fa tlb.o linux-safety, please verify and validate this change. arch/x86/mm/tlb.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index 6b0f4c88b07c..90515c04d90a 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -316,7 +316,7 @@ EXPORT_SYMBOL_GPL(leave_mm); int enable_l1d_flush_for_task(struct task_struct *tsk) { - int cpu, ret = 0, i; + int i; /* * Do not enable L1D_FLUSH_OUT if @@ -329,7 +329,7 @@ int enable_l1d_flush_for_task(struct task_struct *tsk) !static_cpu_has(X86_FEATURE_FLUSH_L1D)) return -EINVAL; - cpu = get_cpu(); + get_cpu(); for_each_cpu(i, &tsk->cpus_mask) { if (cpu_data(i).smt_active == true) { @@ -340,7 +340,7 @@ int enable_l1d_flush_for_task(struct task_struct *tsk) set_ti_thread_flag(&tsk->thread_info, TIF_SPEC_L1D_FLUSH); put_cpu(); - return ret; + return 0; } int disable_l1d_flush_for_task(struct task_struct *tsk) -- 2.17.1