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Diffstat (limited to 'Documentation/locking/spinlocks.rst')
| -rw-r--r-- | Documentation/locking/spinlocks.rst | 16 |
1 files changed, 2 insertions, 14 deletions
diff --git a/Documentation/locking/spinlocks.rst b/Documentation/locking/spinlocks.rst index 098107fb7d86..66e3792f8a36 100644 --- a/Documentation/locking/spinlocks.rst +++ b/Documentation/locking/spinlocks.rst @@ -82,7 +82,7 @@ itself. The read lock allows many concurrent readers. Anything that **changes** the list will have to get the write lock. NOTE! RCU is better for list traversal, but requires careful - attention to design detail (see Documentation/RCU/listRCU.txt). + attention to design detail (see Documentation/RCU/listRCU.rst). Also, you cannot "upgrade" a read-lock to a write-lock, so if you at _any_ time need to do any changes (even if you don't do it every time), you have @@ -90,7 +90,7 @@ to get the write-lock at the very beginning. NOTE! We are working hard to remove reader-writer spinlocks in most cases, so please don't add a new one without consensus. (Instead, see - Documentation/RCU/rcu.txt for complete information.) + Documentation/RCU/rcu.rst for complete information.) ---- @@ -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 ---- |