[rtems commit] libio: Fix deadlock in location management
Sebastian Huber
sebh at rtems.org
Tue Mar 21 15:16:22 UTC 2017
Module: rtems
Branch: 4.11
Commit: f08c71339c05cb462a32a11e3150d71603340e94
Changeset: http://git.rtems.org/rtems/commit/?id=f08c71339c05cb462a32a11e3150d71603340e94
Author: Sebastian Huber <sebastian.huber at embedded-brains.de>
Date: Thu Mar 16 11:54:29 2017 +0100
libio: Fix deadlock in location management
Perform a context-dependent deferred location release to avoid a
deadlock on the file system instance locks, for example during a
chdir().
Close #2936.
---
cpukit/libcsupport/include/rtems/libio_.h | 5 ++++-
cpukit/libcsupport/src/chdir.c | 2 +-
cpukit/libcsupport/src/chroot.c | 4 ++--
cpukit/libcsupport/src/mount.c | 2 +-
cpukit/libcsupport/src/privateenv.c | 4 ++--
cpukit/libcsupport/src/sup_fs_eval_path.c | 4 ++--
cpukit/libcsupport/src/sup_fs_location.c | 9 +++++----
testsuites/fstests/fsnofs01/init.c | 4 ++--
8 files changed, 19 insertions(+), 15 deletions(-)
diff --git a/cpukit/libcsupport/include/rtems/libio_.h b/cpukit/libcsupport/include/rtems/libio_.h
index 0c5e9ed..c2fb975 100644
--- a/cpukit/libcsupport/include/rtems/libio_.h
+++ b/cpukit/libcsupport/include/rtems/libio_.h
@@ -507,11 +507,14 @@ rtems_filesystem_global_location_t *rtems_filesystem_global_location_obtain(
* deferred. The next obtain call will do the actual release.
*
* @param[in] global_loc The global file system location. It must not be NULL.
+ * @param[in] deferred If true, then do a deferred release, otherwise release
+ * it immediately.
*
* @see rtems_filesystem_global_location_obtain().
*/
void rtems_filesystem_global_location_release(
- rtems_filesystem_global_location_t *global_loc
+ rtems_filesystem_global_location_t *global_loc,
+ bool deferred
);
void rtems_filesystem_location_detach(
diff --git a/cpukit/libcsupport/src/chdir.c b/cpukit/libcsupport/src/chdir.c
index 4bcb300..83a359a 100644
--- a/cpukit/libcsupport/src/chdir.c
+++ b/cpukit/libcsupport/src/chdir.c
@@ -39,7 +39,7 @@ int rtems_filesystem_chdir( rtems_filesystem_location_info_t *loc )
);
} else {
rtems_filesystem_location_error( &global_loc->location, ENOTDIR );
- rtems_filesystem_global_location_release( global_loc );
+ rtems_filesystem_global_location_release( global_loc, true );
rv = -1;
}
diff --git a/cpukit/libcsupport/src/chroot.c b/cpukit/libcsupport/src/chroot.c
index 9ec4ad4..0c498e6 100644
--- a/cpukit/libcsupport/src/chroot.c
+++ b/cpukit/libcsupport/src/chroot.c
@@ -80,7 +80,7 @@ int chroot( const char *path )
}
if ( rv != 0 ) {
- rtems_filesystem_global_location_release( new_root_loc );
+ rtems_filesystem_global_location_release( new_root_loc, true );
}
} else {
rv = -1;
@@ -89,7 +89,7 @@ int chroot( const char *path )
rtems_filesystem_eval_path_cleanup( &ctx );
if ( rv != 0 ) {
- rtems_filesystem_global_location_release( new_current_loc );
+ rtems_filesystem_global_location_release( new_current_loc, false );
}
return rv;
diff --git a/cpukit/libcsupport/src/mount.c b/cpukit/libcsupport/src/mount.c
index 0d66477..5328d24 100644
--- a/cpukit/libcsupport/src/mount.c
+++ b/cpukit/libcsupport/src/mount.c
@@ -126,7 +126,7 @@ static int register_subordinate_file_system(
);
rtems_filesystem_mt_unlock();
} else {
- rtems_filesystem_global_location_release( mt_point_node );
+ rtems_filesystem_global_location_release( mt_point_node, true );
}
} else {
rtems_filesystem_eval_path_error( &ctx, EBUSY );
diff --git a/cpukit/libcsupport/src/privateenv.c b/cpukit/libcsupport/src/privateenv.c
index 29821e4..00fc412 100644
--- a/cpukit/libcsupport/src/privateenv.c
+++ b/cpukit/libcsupport/src/privateenv.c
@@ -44,8 +44,8 @@ void rtems_libio_free_user_env(void *arg)
bool uses_global_env = env == &rtems_global_user_env;
if (!uses_global_env) {
- rtems_filesystem_global_location_release(env->current_directory);
- rtems_filesystem_global_location_release(env->root_directory);
+ rtems_filesystem_global_location_release(env->current_directory, false);
+ rtems_filesystem_global_location_release(env->root_directory, false);
free(env);
}
}
diff --git a/cpukit/libcsupport/src/sup_fs_eval_path.c b/cpukit/libcsupport/src/sup_fs_eval_path.c
index 459fa6b..a05472f 100644
--- a/cpukit/libcsupport/src/sup_fs_eval_path.c
+++ b/cpukit/libcsupport/src/sup_fs_eval_path.c
@@ -301,8 +301,8 @@ void rtems_filesystem_eval_path_cleanup(
{
free_location(&ctx->currentloc);
rtems_filesystem_instance_unlock(&ctx->startloc->location);
- rtems_filesystem_global_location_release(ctx->startloc);
- rtems_filesystem_global_location_release(ctx->rootloc);
+ rtems_filesystem_global_location_release(ctx->startloc, false);
+ rtems_filesystem_global_location_release(ctx->rootloc, false);
}
void rtems_filesystem_eval_path_cleanup_with_parent(
diff --git a/cpukit/libcsupport/src/sup_fs_location.c b/cpukit/libcsupport/src/sup_fs_location.c
index ddda4d1..c8956f2 100644
--- a/cpukit/libcsupport/src/sup_fs_location.c
+++ b/cpukit/libcsupport/src/sup_fs_location.c
@@ -105,7 +105,7 @@ void rtems_filesystem_global_location_assign(
*lhs_global_loc_ptr = rhs_global_loc;
rtems_filesystem_mt_entry_unlock(lock_context);
- rtems_filesystem_global_location_release(lhs_global_loc);
+ rtems_filesystem_global_location_release(lhs_global_loc, true);
}
static void release_with_count(
@@ -183,10 +183,11 @@ rtems_filesystem_global_location_t *rtems_filesystem_global_location_obtain(
}
void rtems_filesystem_global_location_release(
- rtems_filesystem_global_location_t *global_loc
+ rtems_filesystem_global_location_t *global_loc,
+ bool deferred
)
{
- if (_Thread_Dispatch_is_enabled()) {
+ if (!deferred) {
release_with_count(global_loc, 1);
} else {
rtems_interrupt_lock_context lock_context;
@@ -232,7 +233,7 @@ void rtems_filesystem_do_unmount(
rtems_filesystem_mt_lock();
rtems_chain_extract_unprotected(&mt_entry->mt_node);
rtems_filesystem_mt_unlock();
- rtems_filesystem_global_location_release(mt_entry->mt_point_node);
+ rtems_filesystem_global_location_release(mt_entry->mt_point_node, false);
(*mt_entry->ops->fsunmount_me_h)(mt_entry);
if (mt_entry->unmount_task != 0) {
diff --git a/testsuites/fstests/fsnofs01/init.c b/testsuites/fstests/fsnofs01/init.c
index f475949..d27b969 100644
--- a/testsuites/fstests/fsnofs01/init.c
+++ b/testsuites/fstests/fsnofs01/init.c
@@ -88,7 +88,7 @@ static void test_location_obtain(void)
rtems_test_assert(node_count(loc_chain) == 1);
rtems_test_assert(null_loc->reference_count == 5);
- rtems_filesystem_global_location_release(null_loc);
+ rtems_filesystem_global_location_release(null_loc, false);
rtems_test_assert(node_count(loc_chain) == 1);
rtems_test_assert(null_loc->reference_count == 4);
@@ -104,7 +104,7 @@ static void test_null_location_obtain(void)
rtems_test_assert(node_count(loc_chain) == 1);
rtems_test_assert(null_loc->reference_count == 5);
- rtems_filesystem_global_location_release(null_loc);
+ rtems_filesystem_global_location_release(null_loc, false);
rtems_test_assert(node_count(loc_chain) == 1);
rtems_test_assert(null_loc->reference_count == 4);
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