Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756747Ab1EPVya (ORCPT ); Mon, 16 May 2011 17:54:30 -0400 Received: from mail-bw0-f46.google.com ([209.85.214.46]:51844 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756422Ab1EPVy3 (ORCPT ); Mon, 16 May 2011 17:54:29 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:x-enigmail-version:content-type :content-transfer-encoding; b=h1wPQkhLVm/e7HZoTfFvXXEIJp7OtnoZKmrBxzrV1eF53FFLshazhTZAedj7BMtk10 cFw+IA6CUSfcZ8gA494+8BFJv5sjRKKSu13kL48SygJiWy/Zr9fzCgQXAE2+loRvXQhr xYioMJ8rRK29MqlQR9+aqbAMKKIBA8iwgM2+s= Message-ID: <4DD19D10.3000201@gmail.com> Date: Mon, 16 May 2011 23:54:24 +0200 From: Jiri Slaby User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; cs-CZ; rv:1.9.2.17) Gecko/20110414 SUSE/3.1.10 Thunderbird/3.1.10 MIME-Version: 1.0 To: John Stultz CC: LKML , "Ted Ts'o" , KOSAKI Motohiro , David Rientjes , Dave Hansen , Andrew Morton , linux-mm@kvack.org Subject: Re: [PATCH 2/3] printk: Add %ptc to safely print a task's comm References: <1305580757-13175-1-git-send-email-john.stultz@linaro.org> <1305580757-13175-3-git-send-email-john.stultz@linaro.org> In-Reply-To: <1305580757-13175-3-git-send-email-john.stultz@linaro.org> X-Enigmail-Version: 1.1.2 Content-Type: text/plain; charset=ISO-8859-2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2099 Lines: 66 On 05/16/2011 11:19 PM, John Stultz wrote: > Accessing task->comm requires proper locking. However in the past > access to current->comm could be done without locking. This > is no longer the case, so all comm access needs to be done > while holding the comm_lock. > > In my attempt to clean up unprotected comm access, I've noticed > most comm access is done for printk output. To simplify correct > locking in these cases, I've introduced a new %ptc format, > which will print the corresponding task's comm. > > Example use: > printk("%ptc: unaligned epc - sending SIGBUS.\n", current); > > CC: Ted Ts'o > CC: KOSAKI Motohiro > CC: David Rientjes > CC: Dave Hansen > CC: Andrew Morton > CC: linux-mm@kvack.org > Signed-off-by: John Stultz > --- > lib/vsprintf.c | 24 ++++++++++++++++++++++++ > 1 files changed, 24 insertions(+), 0 deletions(-) > > diff --git a/lib/vsprintf.c b/lib/vsprintf.c > index bc0ac6b..b7a9953 100644 > --- a/lib/vsprintf.c > +++ b/lib/vsprintf.c > @@ -797,6 +797,23 @@ char *uuid_string(char *buf, char *end, const u8 *addr, > return string(buf, end, uuid, spec); > } > > +static noinline_for_stack Actually, why noinline? Did your previous version have there some TASK_COMM_LEN buffer or anything on stack which is not there anymore? > +char *task_comm_string(char *buf, char *end, void *addr, > + struct printf_spec spec, const char *fmt) > +{ > + struct task_struct *tsk = addr; > + char *ret; > + unsigned long flags; > + > + spin_lock_irqsave(&tsk->comm_lock, flags); > + ret = string(buf, end, tsk->comm, spec); > + spin_unlock_irqrestore(&tsk->comm_lock, flags); > + > + return ret; > +} > + > + > + > int kptr_restrict = 1; > > /* thanks, -- js -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/