Ignore this, the commit message is incorrect. I am sending a V3 On Saturday, September 7, 2019 12:48:41 PM CEST Federico Vaga wrote: > Remove the clever example about read-write lock because these type of > lock is not reccomended anymore (according to the very same document). > So there is no reason to teach cleaver things that people should not do. > > (and by the way there was a little typo) > > Signed-off-by: Federico Vaga <federico.vaga@xxxxxxxxxx> > --- > Documentation/locking/spinlocks.rst | 12 ------------ > 1 file changed, 12 deletions(-) > > diff --git a/Documentation/locking/spinlocks.rst > b/Documentation/locking/spinlocks.rst index e93ec6645238..66e3792f8a36 > 100644 > --- a/Documentation/locking/spinlocks.rst > +++ b/Documentation/locking/spinlocks.rst > @@ -139,18 +139,6 @@ on other CPU's, because an interrupt on another CPU > doesn't interrupt the CPU that holds the lock, so the lock-holder can > continue and eventually releases the lock). > > -Note that you can be clever with read-write locks and interrupts. For > -example, if you know that the interrupt only ever gets a read-lock, then > -you can use a non-irq version of read locks everywhere - because they > -don't block on each other (and thus there is no dead-lock wrt interrupts. > -But when you do the write-lock, you have to use the irq-safe version. > - > -For an example of being clever with rw-locks, see the "waitqueue_lock" > -handling in kernel/sched/core.c - nothing ever _changes_ a wait-queue from > -within an interrupt, they only read the queue in order to know whom to > -wake up. So read-locks are safe (which is good: they are very common > -indeed), while write-locks need to protect themselves against interrupts. > - > Linus > > ----
