lkml.org 
[lkml]   [2010]   [Nov]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [tip:core/urgent] futex: Address compiler warnings in exit_robust_list
    On 11/10/2010 04:30 AM, tip-bot for Darren Hart wrote:
    > Commit-ID: 4c115e951d80aff126468adaec7a6c7854f61ab8
    > Gitweb: http://git.kernel.org/tip/4c115e951d80aff126468adaec7a6c7854f61ab8
    > Author: Darren Hart<dvhart@linux.intel.com>
    > AuthorDate: Thu, 4 Nov 2010 15:00:00 -0400
    > Committer: Thomas Gleixner<tglx@linutronix.de>
    > CommitDate: Wed, 10 Nov 2010 13:27:50 +0100
    >
    > futex: Address compiler warnings in exit_robust_list
    >
    > Since commit 1dcc41bb (futex: Change 3rd arg of fetch_robust_entry()
    > to unsigned int*) some gcc versions decided to emit the following
    > warning:
    >
    > kernel/futex.c: In function ‘exit_robust_list’:
    > kernel/futex.c:2492: warning: ‘next_pi’ may be used uninitialized in this function
    >
    > The commit did not introduce the warning as gcc should have warned
    > before that commit as well. It's just gcc being silly.


    I agree that it should not have - but I did the bisect and this is the
    patch where the warning was first observed. I agree that it is still gcc
    being silly, and I don't know why it treats uninitialized ints different
    than uninitialized unsigned ints (or why it thinks this value is every
    used uninitialized for that matter).

    Thanks for catching the compat-futex.c

    --
    Darren

    >
    > The code path really can't result in next_pi being unitialized (or
    > should not), but let's keep the build clean. Annotate next_pi as an
    > uninitialized_var.
    >
    > [ tglx: Addressed the same issue in futex_compat.c and massaged the
    > changelog ]
    >
    > Signed-off-by: Darren Hart<dvhart@linux.intel.com>
    > Tested-by: Matt Fleming<matt@console-pimps.org>
    > Tested-by: Uwe Kleine-König<u.kleine-koenig@pengutronix.de>
    > Cc: Peter Zijlstra<peterz@infradead.org>
    > Cc: Eric Dumazet<eric.dumazet@gmail.com>
    > Cc: John Kacur<jkacur@redhat.com>
    > Cc: Ingo Molnar<mingo@elte.hu>
    > LKML-Reference:<1288897200-13008-1-git-send-email-dvhart@linux.intel.com>
    > Signed-off-by: Thomas Gleixner<tglx@linutronix.de>
    > ---
    > kernel/futex.c | 3 ++-
    > kernel/futex_compat.c | 3 ++-
    > 2 files changed, 4 insertions(+), 2 deletions(-)
    >
    > diff --git a/kernel/futex.c b/kernel/futex.c
    > index 6c683b3..40a8777 100644
    > --- a/kernel/futex.c
    > +++ b/kernel/futex.c
    > @@ -2489,7 +2489,8 @@ void exit_robust_list(struct task_struct *curr)
    > {
    > struct robust_list_head __user *head = curr->robust_list;
    > struct robust_list __user *entry, *next_entry, *pending;
    > - unsigned int limit = ROBUST_LIST_LIMIT, pi, next_pi, pip;
    > + unsigned int limit = ROBUST_LIST_LIMIT, pi, pip;
    > + unsigned int uninitialized_var(next_pi);
    > unsigned long futex_offset;
    > int rc;
    >
    > diff --git a/kernel/futex_compat.c b/kernel/futex_compat.c
    > index 06da4df..a7934ac 100644
    > --- a/kernel/futex_compat.c
    > +++ b/kernel/futex_compat.c
    > @@ -49,7 +49,8 @@ void compat_exit_robust_list(struct task_struct *curr)
    > {
    > struct compat_robust_list_head __user *head = curr->compat_robust_list;
    > struct robust_list __user *entry, *next_entry, *pending;
    > - unsigned int limit = ROBUST_LIST_LIMIT, pi, next_pi, pip;
    > + unsigned int limit = ROBUST_LIST_LIMIT, pi, pip;
    > + unsigned int uninitialized_var(next_pi);
    > compat_uptr_t uentry, next_uentry, upending;
    > compat_long_t futex_offset;
    > int rc;


    --
    Darren Hart
    Embedded Linux Kernel
    --
    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/

    \
     
     \ /
      Last update: 2010-11-10 17:17    [W:0.028 / U:29.548 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site