Changeset 712c4ba in mainline for kernel/generic/src/synch/spinlock.c

Timestamp:

2011-05-20T16:09:24Z (14 years ago)

Author:

Martin Decky <martin@…>

Branches:

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

Children:

b6f3e7e

Parents:

326bf65

Message:

avoid spinlocks to be taken in the direct code path to physically outputing kconsole characters to the framebuffer (this fixes ticket #243)
the spinlock in printf() (kernel) was sacrificed, this might lead potentially to scrambled kconsole output
the hack of ignoring spinlocks whose names start with "*" in the livelock detector can be removed

File:

• kernel/generic/src/synch/spinlock.c (modified) (1 diff)

kernel/generic/src/synch/spinlock.c

@@ -84 +84 @@
                  * This conserns especially printf_lock and the
                  * framebuffer lock.
-                 *
-                 * Any lock whose name is prefixed by "*" will be
-                 * ignored by this deadlock detection routine
-                 * as this might cause an infinite recursion.
-                 * We trust our code that there is no possible deadlock
-                 * caused by these locks (except when an exception
-                 * is triggered for instance by printf()).
-                 *
-                 * We encountered false positives caused by very
-                 * slow framebuffer interaction (especially when
-                 * run in a simulator) that caused problems with both
-                 * printf_lock and the framebuffer lock.
-                 *
                  */
-                if (lock->name[0] == '*')
-                        continue;
-                
                 if (i++ > DEADLOCK_THRESHOLD) {
                         printf("cpu%u: looping on spinlock %p:%s, "