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| author | Elizabeth Figura <zfigura@codeweavers.com> | 2024-12-13 22:34:45 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-01-08 15:18:10 +0300 |
| commit | cdbb997822806cc1071619b67aef485bb2b921b1 (patch) | |
| tree | e54283ce2dc2e14707d122af3c50d2be5b8b2a5e /include/uapi/linux | |
| parent | b4a7b5fe3f5149fa35278807e0dc13ddb093f4b8 (diff) | |
| download | linux-cdbb997822806cc1071619b67aef485bb2b921b1.tar.xz | |
ntsync: Introduce NTSYNC_IOC_WAIT_ALL.
This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are
simultaneously signaled, and then acquires all of them as a single atomic
operation.
Because acquisition of multiple objects is atomic, some complex locking is
required. We cannot simply spin-lock multiple objects simultaneously, as that
may disable preëmption for a problematically long time.
Instead, modifying any object which may be involved in a wait-all operation takes
a device-wide sleeping mutex, "wait_all_lock", instead of the normal object
spinlock.
Because wait-for-all is a rare operation, in order to optimize wait-for-any,
this lock is only taken when necessary. "all_hint" is used to mark objects which
are involved in a wait-for-all operation, and if an object is not, only its
spinlock is taken.
The locking scheme used here was written by Peter Zijlstra.
Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com>
Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/uapi/linux')
| -rw-r--r-- | include/uapi/linux/ntsync.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/uapi/linux/ntsync.h b/include/uapi/linux/ntsync.h index 40ffdc41d5bb..d64420ffbcd7 100644 --- a/include/uapi/linux/ntsync.h +++ b/include/uapi/linux/ntsync.h @@ -30,6 +30,7 @@ struct ntsync_wait_args { #define NTSYNC_IOC_CREATE_SEM _IOW ('N', 0x80, struct ntsync_sem_args) #define NTSYNC_IOC_WAIT_ANY _IOWR('N', 0x82, struct ntsync_wait_args) +#define NTSYNC_IOC_WAIT_ALL _IOWR('N', 0x83, struct ntsync_wait_args) #define NTSYNC_IOC_SEM_RELEASE _IOWR('N', 0x81, __u32) |