Mathieu Desnoyers c5f58bd58f membarrier: Provide GLOBAL_EXPEDITED command ... Allow expedited membarrier to be used for data shared between processes through shared memory. Processes wishing to receive the membarriers register with MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED. Those which want to issue membarrier invoke MEMBARRIER_CMD_GLOBAL_EXPEDITED. This allows extremely simple kernel-level implementation: we have almost everything we need with the PRIVATE_EXPEDITED barrier code. All we need to do is to add a flag in the mm_struct that will be used to check whether we need to send the IPI to the current thread of each CPU. There is a slight downside to this approach compared to targeting specific shared memory users: when performing a membarrier operation, all registered "global" receivers will get the barrier, even if they don't share a memory mapping with the sender issuing MEMBARRIER_CMD_GLOBAL_EXPEDITED. This registration approach seems to fit the requirement of not disturbing processes that really deeply care about real-time: they simply should not register with MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED. In order to align the membarrier command names, the "MEMBARRIER_CMD_SHARED" command is renamed to "MEMBARRIER_CMD_GLOBAL", keeping an alias of MEMBARRIER_CMD_SHARED to MEMBARRIER_CMD_GLOBAL for UAPI header backward compatibility. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrea Parri <parri.andrea@gmail.com> Cc: Andrew Hunter <ahh@google.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Avi Kivity <avi@scylladb.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Dave Watson <davejwatson@fb.com> Cc: David Sehr <sehr@google.com> Cc: Greg Hackmann <ghackmann@google.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Maged Michael <maged.michael@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-api@vger.kernel.org Link: http://lkml.kernel.org/r/20180129202020.8515-5-mathieu.desnoyers@efficios.com Signed-off-by: Ingo Molnar <mingo@kernel.org>		2018-02-05 21:34:31 +01:00
..
asm-generic	bpf: correct broken uapi for BPF_PROG_TYPE_PERF_EVENT program type	2017-12-05 15:02:40 +01:00
drm	main drm pull request for v4.15	2017-11-15 20:42:10 -08:00
linux	membarrier: Provide GLOBAL_EXPEDITED command	2018-02-05 21:34:31 +01:00
misc	License cleanup: add SPDX license identifier to uapi header files with a license	2017-11-02 11:20:11 +01:00
mtd	License cleanup: add SPDX license identifier to uapi header files with a license	2017-11-02 11:20:11 +01:00
rdma	Updates for 4.15 kernel merge window	2017-11-15 14:54:53 -08:00
scsi	License cleanup: add SPDX license identifier to uapi header files with a license	2017-11-02 11:20:11 +01:00
sound	Merge remote-tracking branches 'asoc/topic/fsl', 'asoc/topic/fsl-ssi', 'asoc/topic/fsl_asrc' and 'asoc/topic/hdac_hdmi' into asoc-next	2018-01-18 11:55:56 +00:00
video	License cleanup: add SPDX license identifier to uapi header files with a license	2017-11-02 11:20:11 +01:00
xen	License cleanup: add SPDX license identifier to uapi header files with a license	2017-11-02 11:20:11 +01:00