Mgerge remote-tracking branch 'torvalds/master' into perf/core

To sync headers, for instance, in this case tools/perf was ahead of
upstream till Linus merged tip/perf/core to get the
PERF_RECORD_TEXT_POKE changes:

  Warning: Kernel ABI header at 'tools/include/uapi/linux/perf_event.h' differs from latest version at 'include/uapi/linux/perf_event.h'
  diff -u tools/include/uapi/linux/perf_event.h include/uapi/linux/perf_event.h

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 35 insertions, 5 deletions

diff --git a/tools/memory-model/README b/tools/memory-model/README
index fc07b52f2028..ecb7385376bf 100644
--- a/tools/memory-model/README
+++ b/tools/memory-model/README
@@ -28,8 +28,34 @@ downloaded separately:
 See "herdtools7/INSTALL.md" for installation instructions.
 
 Note that although these tools usually provide backwards compatibility,
-this is not absolutely guaranteed.  Therefore, if a later version does
-not work, please try using the exact version called out above.
+this is not absolutely guaranteed.
+
+For example, a future version of herd7 might not work with the model
+in this release.  A compatible model will likely be made available in
+a later release of Linux kernel.
+
+If you absolutely need to run the model in this particular release,
+please try using the exact version called out above.
+
+klitmus7 is independent of the model provided here.  It has its own
+dependency on a target kernel release where converted code is built
+and executed.  Any change in kernel APIs essential to klitmus7 will
+necessitate an upgrade of klitmus7.
+
+If you find any compatibility issues in klitmus7, please inform the
+memory model maintainers.
+
+klitmus7 Compatibility Table
+----------------------------
+
+	============  ==========
+	target Linux  herdtools7
+	------------  ----------
+	     -- 4.18  7.48 --
+	4.15 -- 4.19  7.49 --
+	4.20 -- 5.5   7.54 --
+	5.6  --       7.56 --
+	============  ==========
 
 
 ==================
@@ -207,11 +233,15 @@ The Linux-kernel memory model (LKMM) has the following limitations:
 		case as a store release.
 
 	b.	The "unless" RMW operations are not currently modeled:
-		atomic_long_add_unless(), atomic_add_unless(),
-		atomic_inc_unless_negative(), and
-		atomic_dec_unless_positive().  These can be emulated
+		atomic_long_add_unless(), atomic_inc_unless_negative(),
+		and atomic_dec_unless_positive().  These can be emulated
 		in litmus tests, for example, by using atomic_cmpxchg().
 
+		One exception of this limitation is atomic_add_unless(),
+		which is provided directly by herd7 (so no corresponding
+		definition in linux-kernel.def).  atomic_add_unless() is
+		modeled by herd7 therefore it can be used in litmus tests.
+
 	c.	The call_rcu() function is not modeled.  It can be
 		emulated in litmus tests by adding another process that
 		invokes synchronize_rcu() and the body of the callback