Gitweb:
http://git.fedorahosted.org/git/?p=lvm2.git;a=commitdiff;h=16019b518e287d...
Commit: 16019b518e287da19c87eb64229f5c3ca057cb05
Parent: a2d2a61339b83de0d48ed6ed15e816773393c6b4
Author: Alasdair G Kergon <agk(a)redhat.com>
AuthorDate: Thu Apr 28 00:54:27 2016 +0100
Committer: Alasdair G Kergon <agk(a)redhat.com>
CommitterDate: Thu Apr 28 00:54:27 2016 +0100
libdm: Add dm_udev_wait_immediate.
dm_udev_wait() waits inside the library.
dm_udev_wait_immediate allows the caller to do other things if the
cookie isn't yet ready to be decremented.
---
WHATS_NEW_DM | 1 +
libdm/.exported_symbols.DM_1_02_124 | 1 +
libdm/libdevmapper.h | 9 ++++++
libdm/libdm-common.c | 49 +++++++++++++++++++++++++++++++++-
4 files changed, 58 insertions(+), 2 deletions(-)
diff --git a/WHATS_NEW_DM b/WHATS_NEW_DM
index 7460a94..b21d7d5 100644
--- a/WHATS_NEW_DM
+++ b/WHATS_NEW_DM
@@ -1,5 +1,6 @@
Version 1.02.124 -
==================================
+ Add dm_udev_wait_immediate to libdevmapper for waiting outside the library.
Version 1.02.123 - 23rd April 2016
==================================
diff --git a/libdm/.exported_symbols.DM_1_02_124 b/libdm/.exported_symbols.DM_1_02_124
new file mode 100644
index 0000000..934011a
--- /dev/null
+++ b/libdm/.exported_symbols.DM_1_02_124
@@ -0,0 +1 @@
+dm_udev_wait_immediate
diff --git a/libdm/libdevmapper.h b/libdm/libdevmapper.h
index a90013f..d2f40c9 100644
--- a/libdm/libdevmapper.h
+++ b/libdm/libdevmapper.h
@@ -3218,6 +3218,15 @@ int dm_udev_create_cookie(uint32_t *cookie);
int dm_udev_complete(uint32_t cookie);
int dm_udev_wait(uint32_t cookie);
+/*
+ * dm_dev_wait_immediate
+ * If *ready is 1 on return, the wait is complete.
+ * If *ready is 0 on return, the wait is incomplete and either
+ * this function or dm_udev_wait() must be called again.
+ * Returns 0 on error, when neither function should be called again.
+ */
+int dm_udev_wait_immediate(uint32_t cookie, int *ready);
+
#define DM_DEV_DIR_UMASK 0022
#define DM_CONTROL_NODE_UMASK 0177
diff --git a/libdm/libdm-common.c b/libdm/libdm-common.c
index 2580d94..d67d0bb 100644
--- a/libdm/libdm-common.c
+++ b/libdm/libdm-common.c
@@ -2082,6 +2082,14 @@ int dm_udev_wait(uint32_t cookie)
return 1;
}
+int dm_udev_wait_immediate(uint32_t cookie, int *ready)
+{
+ update_devs();
+ *ready = 1;
+
+ return 1;
+}
+
#else /* UDEV_SYNC_SUPPORT */
static int _check_semaphore_is_supported(void)
@@ -2506,10 +2514,16 @@ int dm_udev_complete(uint32_t cookie)
return 1;
}
-static int _udev_wait(uint32_t cookie)
+/*
+ * If *nowait is set, return immediately leaving it set if the semaphore
+ * is not ready to be decremented to 0. *nowait is cleared if the wait
+ * succeeds.
+ */
+static int _udev_wait(uint32_t cookie, int *nowait)
{
int semid;
struct sembuf sb = {0, 0, 0};
+ int val;
if (!cookie || !dm_udev_get_sync_support())
return 1;
@@ -2517,6 +2531,21 @@ static int _udev_wait(uint32_t cookie)
if (!_get_cookie_sem(cookie, &semid))
return_0;
+ /* Return immediately if the semaphore value exceeds 1? */
+ if (*nowait) {
+ if ((val = semctl(semid, 0, GETVAL)) < 0) {
+ log_error("semid %d: sem_ctl GETVAL failed for "
+ "cookie 0x%" PRIx32 ": %s",
+ semid, cookie, strerror(errno));
+ return 0;
+ }
+
+ if (val > 1)
+ return 1;
+
+ *nowait = 0;
+ }
+
if (!_udev_notify_sem_dec(cookie, semid)) {
log_error("Failed to set a proper state for notification "
"semaphore identified by cookie value %" PRIu32 " (0x%x) "
@@ -2548,11 +2577,27 @@ repeat_wait:
int dm_udev_wait(uint32_t cookie)
{
- int r = _udev_wait(cookie);
+ int nowait = 0;
+ int r = _udev_wait(cookie, &nowait);
update_devs();
return r;
}
+int dm_udev_wait_immediate(uint32_t cookie, int *ready)
+{
+ int nowait = 1;
+ int r = _udev_wait(cookie, &nowait);
+
+ if (r && nowait) {
+ *ready = 0;
+ return 1;
+ }
+
+ update_devs();
+ *ready = 1;
+
+ return r;
+}
#endif /* UDEV_SYNC_SUPPORT */