From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f178.google.com (mail-wi0-f178.google.com [209.85.212.178]) by kanga.kvack.org (Postfix) with ESMTP id C3BBC6B00A8 for ; Fri, 13 Dec 2013 09:57:08 -0500 (EST) Received: by mail-wi0-f178.google.com with SMTP id bz8so1177988wib.11 for ; Fri, 13 Dec 2013 06:57:08 -0800 (PST) Received: from mail-we0-x22e.google.com (mail-we0-x22e.google.com [2a00:1450:400c:c03::22e]) by mx.google.com with ESMTPS id t2si1138350wiz.3.2013.12.13.06.57.08 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 13 Dec 2013 06:57:08 -0800 (PST) Received: by mail-we0-f174.google.com with SMTP id q58so1981361wes.19 for ; Fri, 13 Dec 2013 06:57:08 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <52AB1875.2090207@tycho.nsa.gov> References: <1386018639-18916-1-git-send-email-wroberts@tresys.com> <1386018639-18916-3-git-send-email-wroberts@tresys.com> <52AB1875.2090207@tycho.nsa.gov> Date: Fri, 13 Dec 2013 09:57:07 -0500 Message-ID: Subject: Re: [PATCH 2/3] proc: Update get proc_pid_cmdline() to use mm.h helpers From: William Roberts Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Stephen Smalley Cc: "linux-audit@redhat.com" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Richard Guy Briggs , "viro@zeniv.linux.org.uk" , William Roberts On Fri, Dec 13, 2013 at 9:23 AM, Stephen Smalley wrote: > On 12/02/2013 04:10 PM, William Roberts wrote: >> Re-factor proc_pid_cmdline() to use get_cmdline_length() and >> copy_cmdline() helpers from mm.h >> >> Signed-off-by: William Roberts >> --- >> fs/proc/base.c | 35 ++++++++++------------------------- >> 1 file changed, 10 insertions(+), 25 deletions(-) >> >> diff --git a/fs/proc/base.c b/fs/proc/base.c >> index 03c8d74..fb4eda5 100644 >> --- a/fs/proc/base.c >> +++ b/fs/proc/base.c >> @@ -203,37 +203,22 @@ static int proc_root_link(struct dentry *dentry, struct path *path) >> static int proc_pid_cmdline(struct task_struct *task, char * buffer) >> { >> int res = 0; >> - unsigned int len; >> + unsigned int len = 0; > > Why? You set len below before first use, so this is redundant. > Yep you're right. >> struct mm_struct *mm = get_task_mm(task); >> if (!mm) >> - goto out; >> - if (!mm->arg_end) >> - goto out_mm; /* Shh! No looking before we're done */ >> + return 0; > > Equivalent to goto out in the original code, so why change it? Don't > make unnecessary changes. > > Also, I think the get_task_mm() ought to move into the helper (or all of > proc_pid_cmdline() should just become the helper). In what situation > will you not be calling get_task_mm() and mmput() around every call to > the helper? Again my thought on this is to reduce get_task_mm() and mmput() calls. How expensive are they, etc. However, just to recap the other email. If we move to saying the audit cache of this can be capped at PATH_MAX even if it results in some wasted memory, we can just take the original procfs code and add a length argument. > >> >> - len = mm->arg_end - mm->arg_start; >> - >> + len = get_cmdline_length(mm); >> + if (!len) >> + goto mm_out; > > Could be moved into the helper. Not sure how the inline function helps > readability or maintainability. Sure... mostly for readability. > >> + >> + /*The caller of this allocates a page */ >> if (len > PAGE_SIZE) >> len = PAGE_SIZE; > > If the capping of len is handled by the caller, then pass an int to your > helper rather than an unsigned int to avoid problems later with > access_process_vm(). Ok... just weird that lengths are signed to me. when will you ever have negative space? > >> -out_mm: >> + >> + res = copy_cmdline(task, mm, buffer, len); >> +mm_out: >> mmput(mm); > > Odd style. If there is only one exit path, just call it out; if there > are two, keep them as out_mm and out. > Yes their is only 1 jmp label. Your right, this is odd. >> -out: >> return res; >> } >> >> > -- Respectfully, William C Roberts -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org