From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f46.google.com (mail-pj1-f46.google.com [209.85.216.46]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E182FC2E7 for ; Fri, 31 Mar 2023 04:12:01 +0000 (UTC) Received: by mail-pj1-f46.google.com with SMTP id h12-20020a17090aea8c00b0023d1311fab3so22076316pjz.1 for ; Thu, 30 Mar 2023 21:12:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1680235921; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=/fL6uYJqAJu4UWRofGL+uAKGAJCdSLBsLiJ3MZGh5jk=; b=e4BTX608wtZj4jZHDmB/1T4Gq8gzXBUP6DMAygN96mFzBhJbH8TFT2/VfRMayOo63G lTCJQFkxdohuSxvSyi7wtdj2gzFs7VUaboL5Yk1trxL9GdyiC7tFJelssEv8eqjpqdQG YLkdiqsWKS6TtftuVgzjuJki5n6e12uuDQlDw= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680235921; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=/fL6uYJqAJu4UWRofGL+uAKGAJCdSLBsLiJ3MZGh5jk=; b=A+cWtCeqaZsmJMJnFlMdDGxqJ2ntwnyM8EH8O3AS9swLNG/eUkb/+qN43DP8uU0B1P qVS71/xSynqWk3Rm5Eul0REJbPhCnE0PToVhv0pQPBKQnEmoizMa5q056Jqv/23+gmPM oUwGIhodqYVrTghz79SoJVRNFa1I1+/qr9j5b8G3QeSwMGW+E8ojurA3gAlrnJK2LJVu ELzPIcqyT0gVy0cH/+phc8FeszDEkkisboCErht1yb+Zb2i8zbG+2gSYvTaR21ybZ6Oy E3pCdsK7mziePBvA7dk8MDKYfYuwwecJE/NQHjeDKqC7GZbZyOlMeetjIXfeu3qPNSII A+zA== X-Gm-Message-State: AAQBX9dyD4NLXj1iE3Yl9lhptNl24qRjUMW6Vm4xeP58+WDmcXLKBhsL CA6r44jC6WWmlc+6Ex/lZqV6IQ== X-Google-Smtp-Source: AKy350Z3RDbX1XH78O/Mn6Z/g1q+VldEMG0p2DTAFVaet1gIF+cSHwqqrndzG46RRYMeO2Fqm8seLQ== X-Received: by 2002:a17:90b:3b83:b0:236:a3c2:168a with SMTP id pc3-20020a17090b3b8300b00236a3c2168amr28524828pjb.33.1680235921307; Thu, 30 Mar 2023 21:12:01 -0700 (PDT) Received: from google.com (KD124209188001.ppp-bb.dion.ne.jp. [124.209.188.1]) by smtp.gmail.com with ESMTPSA id c3-20020a170902aa4300b0019f2a7f4d16sm506889plr.39.2023.03.30.21.11.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Mar 2023 21:12:00 -0700 (PDT) Date: Fri, 31 Mar 2023 13:11:54 +0900 From: Sergey Senozhatsky To: Luis Chamberlain Cc: Linus Torvalds , Peter Zijlstra , Petr Mladek , Sergey Senozhatsky , david@redhat.com, patches@lists.linux.dev, linux-modules@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, petr.pavlu@suse.com, prarit@redhat.com, gregkh@linuxfoundation.org, rafael@kernel.org, christophe.leroy@csgroup.eu, tglx@linutronix.de, song@kernel.org, rppt@kernel.org, willy@infradead.org, vbabka@suse.cz, mhocko@suse.com, dave.hansen@linux.intel.com Subject: Re: [PATCH 4/7] sempahore: add a helper for a concurrency limiter Message-ID: <20230331041154.GC12892@google.com> References: <20230329053149.3976378-1-mcgrof@kernel.org> <20230329053149.3976378-5-mcgrof@kernel.org> <20230329072112.GG4253@hirez.programming.kicks-ass.net> <20230329091935.GP4253@hirez.programming.kicks-ass.net> <20230330115626.GA124812@hirez.programming.kicks-ass.net> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On (23/03/30 20:45), Luis Chamberlain wrote: [..] > -static DEFINE_SEMAPHORE(console_sem); > +static DEFINE_MUTEX(console_sem); > HLIST_HEAD(console_list); > EXPORT_SYMBOL_GPL(console_list); > DEFINE_STATIC_SRCU(console_srcu); > @@ -309,7 +309,7 @@ EXPORT_SYMBOL(console_srcu_read_unlock); > * macros instead of functions so that _RET_IP_ contains useful information. > */ > #define down_console_sem() do { \ > - down(&console_sem);\ > + mutex_lock(&console_sem);\ > mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);\ > } while (0) > > @@ -324,7 +324,7 @@ static int __down_trylock_console_sem(unsigned long ip) > * deadlock in printk()->down_trylock_console_sem() otherwise. > */ > printk_safe_enter_irqsave(flags); > - lock_failed = down_trylock(&console_sem); > + lock_failed = !mutex_trylock(&console_sem); > printk_safe_exit_irqrestore(flags); > > if (lock_failed) > @@ -341,7 +341,7 @@ static void __up_console_sem(unsigned long ip) > mutex_release(&console_lock_dep_map, ip); > > printk_safe_enter_irqsave(flags); > - up(&console_sem); > + mutex_unlock(&console_sem); mutex_unlock() does not like when its called from IRQ, so this is not going to work very well.