Changeset 2b4a9f26 in mainline for kernel/doc/synchronization

Timestamp:

2010-05-20T19:30:18Z (14 years ago)

Author:

Martin Decky <martin@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

42bbbe2

Parents:

b10e6e31

Message:

Add interrupts-disabled spinlocks whose purpose is the semantic distinction between spinlocks acquired always with interrupts disabled and normal spinlocks.
The compile-time distinction is implemented by the means of the type system and basic code correctness properties can be checked by the debugging assertions during run-time (with CONFIG_DEBUG)

• Correct bracketing of top-level interrupts-disabled spinlocks
• Correctness of the use of nested interrupts-disabled spinlocks (interrupts must be actually disabled)
• Basic consistency of places where the interrupt level is restored

The API encapsulates the physical manipulation with the interrupt levels and also two common locking patterns

• Sequential unlocking of spinlock A before locking of spinlock B without restoring original interrupt level (irq_spinlock_pass())
• Hand-over-hand locking of two locks in the correct locking order, e.g. if A precedes B, then locking of B before unlocking A (irq_spinlock_exchange())

A new HAL function interrupts_disabled() should be implemented in each port to support the run-time checks of correctly disabled interrupts while locking nested interrupts-disabled spinlocks
(only in debug builds, not used in non-debug builds).

File:

• kernel/doc/synchronization (modified) (3 diffs)

kernel/doc/synchronization

@@ -5 +5 @@
                                  | spinlock_t |
                                  +------------+
+                                       |
+                                       +------------------------------+
+                                                                      |
+                      INTERRUPTS-DISABLED SPINNING LOCKS              |
+       irq_spinlock_lock, irq_spinlock_trylock, irq_spinlock_unlock   |
+                               +----------------+                     |
+                               | irq_spinlock_t |<--------------------+
+                               +----------------+
+
+
 
                                    WAIT QUEUES
@@ -10 +20 @@
                                    +---------+
                                    | waitq_t |
-                                   +---------+
-                                  /           \
+                                   +---------+
+                                  /           \
                SEMAPHORES        /             \  CONDITION VARIABLES
  semaphore_down_timeout, semaphore_up    condvar_wait_timeout, condvar_signal
@@ -18 +28 @@
             +--------------+                         +-----------+
                    |                                       ^
-                   |                                       |
+                   |                                       |
                    |                                +------+
-                   V                               /           
+                   V                               /
                 MUTEXES                           / READERS/WRITERS LOCKS
     mutex_lock_timeout, mutex_unlock   rwlock_reader/writer_lock_timeout, rwlock_unlock
               +---------+                       /        +----------+
-              | mutex_t |------------------------------->| rwlock_t |
-              +---------+                     /          +----------+
-                   |                         /
-                   +------------------------+
+              | mutex_t |------------------------------->| rwlock_t |
+              +---------+                     /          +----------+
+                   |                         /
+                   +------------------------+