On 03/16/15 00:10, Rabin Vincent wrote:
On Sun, Mar 15, 2015 at 11:49:07PM +0200, Matthias Bonne wrote:
So the counter is set to 1 before taking the spinlock, which I think
might cause the race. Did I miss something?
Yes, you miss the fact that __mutex_slowpath_needs_to_unlock() is 0 for
the C
On Sun, 2015-03-15 at 15:18 -0700, Davidlohr Bueso wrote:
> Correct, in debug this is most likely true, yet safe because everything
^^^ false, again the same reasoning.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of
On Sun, 2015-03-15 at 23:49 +0200, Matthias Bonne wrote:
> On 03/15/15 03:09, Davidlohr Bueso wrote:
> > On Sat, 2015-03-14 at 18:03 -0700, Davidlohr Bueso wrote:
> >> Good analysis, but not quite accurate for one simple fact: mutex
> >> trylocks _only_ use fastpaths (obviously just depend on the c
On Sun, Mar 15, 2015 at 11:49:07PM +0200, Matthias Bonne wrote:
> So both mutex_trylock() and mutex_unlock() always use the slow paths.
> The slowpath for mutex_unlock() is __mutex_unlock_slowpath(), which
> simply calls __mutex_unlock_common_slowpath(), and the latter starts
> like this:
>
>
On 03/15/15 03:09, Davidlohr Bueso wrote:
On Sat, 2015-03-14 at 18:03 -0700, Davidlohr Bueso wrote:
Good analysis, but not quite accurate for one simple fact: mutex
trylocks _only_ use fastpaths (obviously just depend on the counter
cmpxchg to 0), so you never fallback to the slowpath you are me
On Sat, 2015-03-14 at 18:03 -0700, Davidlohr Bueso wrote:
> Good analysis, but not quite accurate for one simple fact: mutex
> trylocks _only_ use fastpaths (obviously just depend on the counter
> cmpxchg to 0), so you never fallback to the slowpath you are mentioning,
> thus the race is non existe
On Sun, 2015-03-15 at 01:05 +0200, Matthias Bonne wrote:
> On 03/10/15 15:03, Yann Droneaud wrote:
> > Hi,
> >
> > Le mercredi 04 mars 2015 à 02:13 +0200, Matthias Bonne a écrit :
> >
> >> I am trying to understand how mutexes work in the kernel, and I think
> >> there might be a race between mutex
On 03/10/15 16:59, valdis.kletni...@vt.edu wrote:
On Tue, 10 Mar 2015 14:03:59 +0100, Yann Droneaud said:
Consider the following sequence of events:
0. Suppose a mutex is locked by task A and has no waiters.
1. Task B calls mutex_trylock().
2. mutex_trylock() calls the architecture-specific
On 03/10/15 15:03, Yann Droneaud wrote:
Hi,
Le mercredi 04 mars 2015 à 02:13 +0200, Matthias Bonne a écrit :
I am trying to understand how mutexes work in the kernel, and I think
there might be a race between mutex_trylock() and mutex_unlock(). More
specifically, the race is between the functi
On Tue, 10 Mar 2015 14:03:59 +0100, Yann Droneaud said:
> > Consider the following sequence of events:
> >
> > 0. Suppose a mutex is locked by task A and has no waiters.
> >
> > 1. Task B calls mutex_trylock().
> >
> > 2. mutex_trylock() calls the architecture-specific
> > __mutex_fastpath_
Hi,
Le mercredi 04 mars 2015 à 02:13 +0200, Matthias Bonne a écrit :
> I am trying to understand how mutexes work in the kernel, and I think
> there might be a race between mutex_trylock() and mutex_unlock(). More
> specifically, the race is between the functions
> __mutex_trylock_slowpath and __
11 matches
Mail list logo
