[src/trunk]: src/sys/external/bsd/drm2/linux linux: Teach rw semaphores about...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/78175f98c8e1
branches:  trunk
changeset: 1028576:78175f98c8e1
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Sun Dec 19 11:21:45 2021 +0000

description:
linux: Teach rw semaphores about lockdebug.

diffstat:

 sys/external/bsd/drm2/include/linux/rwsem.h |   3 +-
 sys/external/bsd/drm2/linux/linux_rwsem.c   |  68 ++++++++++++++++++++++++++++-
 2 files changed, 68 insertions(+), 3 deletions(-)

diffs (184 lines):

diff -r 3b192e349e04 -r 78175f98c8e1 sys/external/bsd/drm2/include/linux/rwsem.h
--- a/sys/external/bsd/drm2/include/linux/rwsem.h       Sun Dec 19 11:21:38 2021 +0000
+++ b/sys/external/bsd/drm2/include/linux/rwsem.h       Sun Dec 19 11:21:45 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: rwsem.h,v 1.3 2021/12/19 11:21:30 riastradh Exp $      */
+/*     $NetBSD: rwsem.h,v 1.4 2021/12/19 11:21:45 riastradh Exp $      */
 
 /*-
  * Copyright (c) 2014 The NetBSD Foundation, Inc.
@@ -60,6 +60,7 @@
        struct lwp      *rws_writer;
        unsigned        rws_readers;
        bool            rws_writewanted;
+       bool            rws_debug;
 };
 
 void init_rwsem(struct rw_semaphore *);
diff -r 3b192e349e04 -r 78175f98c8e1 sys/external/bsd/drm2/linux/linux_rwsem.c
--- a/sys/external/bsd/drm2/linux/linux_rwsem.c Sun Dec 19 11:21:38 2021 +0000
+++ b/sys/external/bsd/drm2/linux/linux_rwsem.c Sun Dec 19 11:21:45 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: linux_rwsem.c,v 1.2 2021/12/19 11:21:38 riastradh Exp $        */
+/*     $NetBSD: linux_rwsem.c,v 1.3 2021/12/19 11:21:45 riastradh Exp $        */
 
 /*-
  * Copyright (c) 2021 The NetBSD Foundation, Inc.
@@ -27,12 +27,13 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: linux_rwsem.c,v 1.2 2021/12/19 11:21:38 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: linux_rwsem.c,v 1.3 2021/12/19 11:21:45 riastradh Exp $");
 
 #include <sys/types.h>
 
 #include <sys/condvar.h>
 #include <sys/lwp.h>
+#include <sys/lockdebug.h>
 #include <sys/rwlock.h>
 
 #include <machine/limits.h>
@@ -41,6 +42,40 @@
 
 #include <linux/rwsem.h>
 
+#define        RWSEM_WANTLOCK(RWSEM)                                                 \
+       LOCKDEBUG_WANTLOCK((RWSEM)->rws_debug, (RWSEM),                       \
+           (uintptr_t)__builtin_return_address(0), 0)
+#define        RWSEM_LOCKED_EX(RWSEM)                                                \
+       LOCKDEBUG_LOCKED((RWSEM)->rws_debug, (RWSEM), NULL,                   \
+           (uintptr_t)__builtin_return_address(0), 0)
+#define        RWSEM_LOCKED_SH(RWSEM)                                                \
+       LOCKDEBUG_LOCKED((RWSEM)->rws_debug, (RWSEM), NULL,                   \
+           (uintptr_t)__builtin_return_address(0), 1)
+#define        RWSEM_UNLOCKED_EX(RWSEM)                                              \
+       LOCKDEBUG_UNLOCKED((RWSEM)->rws_debug, (RWSEM),                       \
+           (uintptr_t)__builtin_return_address(0), 0)
+#define        RWSEM_UNLOCKED_SH(RWSEM)                                              \
+       LOCKDEBUG_UNLOCKED((RWSEM)->rws_debug, (RWSEM),                       \
+           (uintptr_t)__builtin_return_address(0), 1)
+
+#ifdef LOCKDEBUG
+static void
+rwsem_dump(const volatile void *cookie, lockop_printer_t pr)
+{
+       const volatile struct rw_semaphore *rwsem = cookie;
+
+       pr("%-13s: %p", "writer", rwsem->rws_writer);
+       pr("%-13s: %u", "readers", rwsem->rws_readers);
+       pr("%-13s: %s", "writewanted", rwsem->rws_writewanted ? "yes" : "no");
+}
+
+static lockops_t rwsem_lockops = {
+       .lo_name = "Linux read/write semaphore",
+       .lo_type = LOCKOPS_SLEEP,
+       .lo_dump = rwsem_dump,
+};
+#endif
+
 void
 init_rwsem(struct rw_semaphore *rwsem)
 {
@@ -49,6 +84,11 @@
        cv_init(&rwsem->rws_cv, "lnxrwsem");
        rwsem->rws_writer = NULL;
        rwsem->rws_readers = 0;
+
+#ifdef LOCKDEBUG
+       rwsem->rws_debug = LOCKDEBUG_ALLOC(rwsem, &rwsem_lockops,
+           (uintptr_t)__builtin_return_address(0));
+#endif
 }
 
 void
@@ -57,6 +97,11 @@
 
        KASSERT(rwsem->rws_readers == 0);
        KASSERT(rwsem->rws_writer == NULL);
+
+#ifdef LOCKDEBUG
+       LOCKDEBUG_FREE(rwsem->rws_debug, rwsem);
+#endif
+
        cv_destroy(&rwsem->rws_cv);
        mutex_destroy(&rwsem->rws_lock);
 }
@@ -65,12 +110,16 @@
 down_read(struct rw_semaphore *rwsem)
 {
 
+       RWSEM_WANTLOCK(rwsem);
+
        mutex_enter(&rwsem->rws_lock);
        while (rwsem->rws_writer || rwsem->rws_writewanted)
                cv_wait(&rwsem->rws_cv, &rwsem->rws_lock);
        KASSERT(rwsem->rws_readers < UINT_MAX);
        rwsem->rws_readers++;
        mutex_exit(&rwsem->rws_lock);
+
+       RWSEM_LOCKED_SH(rwsem);
 }
 
 bool
@@ -94,6 +143,9 @@
        }
        mutex_exit(&rwsem->rws_lock);
 
+       if (ret)
+               RWSEM_LOCKED_SH(rwsem);
+
        return ret;
 }
 
@@ -101,6 +153,8 @@
 up_read(struct rw_semaphore *rwsem)
 {
 
+       RWSEM_UNLOCKED_SH(rwsem);
+
        mutex_enter(&rwsem->rws_lock);
        KASSERT(rwsem->rws_readers);
        KASSERT(rwsem->rws_writer == NULL);
@@ -113,6 +167,8 @@
 down_write(struct rw_semaphore *rwsem)
 {
 
+       RWSEM_WANTLOCK(rwsem);
+
        mutex_enter(&rwsem->rws_lock);
 
        /* If another writer is waiting, get in the queue.  */
@@ -138,12 +194,16 @@
        rwsem->rws_writer = curlwp;
 
        mutex_exit(&rwsem->rws_lock);
+
+       RWSEM_LOCKED_EX(rwsem);
 }
 
 void
 up_write(struct rw_semaphore *rwsem)
 {
 
+       RWSEM_UNLOCKED_EX(rwsem);
+
        mutex_enter(&rwsem->rws_lock);
        KASSERT(rwsem->rws_writer == curlwp);
        KASSERT(rwsem->rws_readers == 0);
@@ -156,6 +216,8 @@
 downgrade_write(struct rw_semaphore *rwsem)
 {
 
+       RWSEM_UNLOCKED_EX(rwsem);
+
        mutex_enter(&rwsem->rws_lock);
        KASSERT(rwsem->rws_writer == curlwp);
        KASSERT(rwsem->rws_readers == 0);
@@ -163,4 +225,6 @@
        rwsem->rws_readers = 1;
        cv_broadcast(&rwsem->rws_cv);
        mutex_exit(&rwsem->rws_lock);
+
+       RWSEM_LOCKED_SH(rwsem);
 }