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authorLinus Torvalds <torvalds@linux-foundation.org>2018-02-06 19:57:31 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-02-06 19:57:31 -0800
commitab2d92ad881da11331280aedf612d82e61cb6d41 (patch)
treeea1bc914b9dfc510b7ea7ec21219f0f831c442cc /include/uapi/linux
parent4b0dda4f86c5c87698f7228a4f65ef834dc79252 (diff)
parent82845079160817cc6ac64e5321bbd935e0a47b3a (diff)
Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar: - membarrier updates (Mathieu Desnoyers) - SMP balancing optimizations (Mel Gorman) - stats update optimizations (Peter Zijlstra) - RT scheduler race fixes (Steven Rostedt) - misc fixes and updates * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/fair: Use a recently used CPU as an idle candidate and the basis for SIS sched/fair: Do not migrate if the prev_cpu is idle sched/fair: Restructure wake_affine*() to return a CPU id sched/fair: Remove unnecessary parameters from wake_affine_idle() sched/rt: Make update_curr_rt() more accurate sched/rt: Up the root domain ref count when passing it around via IPIs sched/rt: Use container_of() to get root domain in rto_push_irq_work_func() sched/core: Optimize update_stats_*() sched/core: Optimize ttwu_stat() membarrier/selftest: Test private expedited sync core command membarrier/arm64: Provide core serializing command membarrier/x86: Provide core serializing command membarrier: Provide core serializing command, *_SYNC_CORE lockin/x86: Implement sync_core_before_usermode() locking: Introduce sync_core_before_usermode() membarrier/selftest: Test global expedited command membarrier: Provide GLOBAL_EXPEDITED command membarrier: Document scheduler barrier requirements powerpc, membarrier: Skip memory barrier in switch_mm() membarrier/selftest: Test private expedited command
Diffstat (limited to 'include/uapi/linux')
-rw-r--r--include/uapi/linux/membarrier.h74
1 files changed, 66 insertions, 8 deletions
diff --git a/include/uapi/linux/membarrier.h b/include/uapi/linux/membarrier.h
index 4e01ad7ffe98..5891d7614c8c 100644
--- a/include/uapi/linux/membarrier.h
+++ b/include/uapi/linux/membarrier.h
@@ -31,7 +31,7 @@
* enum membarrier_cmd - membarrier system call command
* @MEMBARRIER_CMD_QUERY: Query the set of supported commands. It returns
* a bitmask of valid commands.
- * @MEMBARRIER_CMD_SHARED: Execute a memory barrier on all running threads.
+ * @MEMBARRIER_CMD_GLOBAL: Execute a memory barrier on all running threads.
* Upon return from system call, the caller thread
* is ensured that all running threads have passed
* through a state where all memory accesses to
@@ -40,6 +40,28 @@
* (non-running threads are de facto in such a
* state). This covers threads from all processes
* running on the system. This command returns 0.
+ * @MEMBARRIER_CMD_GLOBAL_EXPEDITED:
+ * Execute a memory barrier on all running threads
+ * of all processes which previously registered
+ * with MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED.
+ * Upon return from system call, the caller thread
+ * is ensured that all running threads have passed
+ * through a state where all memory accesses to
+ * user-space addresses match program order between
+ * entry to and return from the system call
+ * (non-running threads are de facto in such a
+ * state). This only covers threads from processes
+ * which registered with
+ * MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED.
+ * This command returns 0. Given that
+ * registration is about the intent to receive
+ * the barriers, it is valid to invoke
+ * MEMBARRIER_CMD_GLOBAL_EXPEDITED from a
+ * non-registered process.
+ * @MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED:
+ * Register the process intent to receive
+ * MEMBARRIER_CMD_GLOBAL_EXPEDITED memory
+ * barriers. Always returns 0.
* @MEMBARRIER_CMD_PRIVATE_EXPEDITED:
* Execute a memory barrier on each running
* thread belonging to the same process as the current
@@ -51,7 +73,7 @@
* to and return from the system call
* (non-running threads are de facto in such a
* state). This only covers threads from the
- * same processes as the caller thread. This
+ * same process as the caller thread. This
* command returns 0 on success. The
* "expedited" commands complete faster than
* the non-expedited ones, they never block,
@@ -64,18 +86,54 @@
* Register the process intent to use
* MEMBARRIER_CMD_PRIVATE_EXPEDITED. Always
* returns 0.
+ * @MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE:
+ * In addition to provide memory ordering
+ * guarantees described in
+ * MEMBARRIER_CMD_PRIVATE_EXPEDITED, ensure
+ * the caller thread, upon return from system
+ * call, that all its running threads siblings
+ * have executed a core serializing
+ * instruction. (architectures are required to
+ * guarantee that non-running threads issue
+ * core serializing instructions before they
+ * resume user-space execution). This only
+ * covers threads from the same process as the
+ * caller thread. This command returns 0 on
+ * success. The "expedited" commands complete
+ * faster than the non-expedited ones, they
+ * never block, but have the downside of
+ * causing extra overhead. If this command is
+ * not implemented by an architecture, -EINVAL
+ * is returned. A process needs to register its
+ * intent to use the private expedited sync
+ * core command prior to using it, otherwise
+ * this command returns -EPERM.
+ * @MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_SYNC_CORE:
+ * Register the process intent to use
+ * MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE.
+ * If this command is not implemented by an
+ * architecture, -EINVAL is returned.
+ * Returns 0 on success.
+ * @MEMBARRIER_CMD_SHARED:
+ * Alias to MEMBARRIER_CMD_GLOBAL. Provided for
+ * header backward compatibility.
*
* Command to be passed to the membarrier system call. The commands need to
* be a single bit each, except for MEMBARRIER_CMD_QUERY which is assigned to
* the value 0.
*/
enum membarrier_cmd {
- MEMBARRIER_CMD_QUERY = 0,
- MEMBARRIER_CMD_SHARED = (1 << 0),
- /* reserved for MEMBARRIER_CMD_SHARED_EXPEDITED (1 << 1) */
- /* reserved for MEMBARRIER_CMD_PRIVATE (1 << 2) */
- MEMBARRIER_CMD_PRIVATE_EXPEDITED = (1 << 3),
- MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED = (1 << 4),
+ MEMBARRIER_CMD_QUERY = 0,
+ MEMBARRIER_CMD_GLOBAL = (1 << 0),
+ MEMBARRIER_CMD_GLOBAL_EXPEDITED = (1 << 1),
+ MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED = (1 << 2),
+ MEMBARRIER_CMD_PRIVATE_EXPEDITED = (1 << 3),
+ MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED = (1 << 4),
+ MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE = (1 << 5),
+ MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_SYNC_CORE = (1 << 6),
+
+ /* Alias for header backward compatibility. */
+ MEMBARRIER_CMD_SHARED = MEMBARRIER_CMD_GLOBAL,
};
#endif /* _UAPI_LINUX_MEMBARRIER_H */

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