[2.28 COMMITTED] RISC-V: don't assume PI mutexes and robust futexes before 4.20 (bug 23864)

[2.28 COMMITTED] RISC-V: don't assume PI mutexes and robust futexes before 4.20 (bug 23864)

[Aurelien Jarno]

From: Andreas Schwab <schwab@suse.de>

Support for futex_cmpxchg as only been added to 4.20-rc1.

(cherry picked from commit 295132ff052b32960207d82a950c0efbf0766857)
---
 ChangeLog                                       | 7 +++++++
 NEWS                                            | 1 +
 sysdeps/unix/sysv/linux/riscv/kernel-features.h | 5 +++++
 3 files changed, 13 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index 42fe0aeb1e5..e5011123eb7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2018-11-07  Andreas Schwab  <schwab@suse.de>
+
+	[BZ #23864]
+	* sysdeps/unix/sysv/linux/riscv/kernel-features.h
+	(__ASSUME_SET_ROBUST_LIST) [__LINUX_KERNEL_VERSION < 0x041400]:
+	Undef.
+
 2018-09-21  Adhemerval Zanella  <adhemerval.zanella@linaro.org>
 
 	* NEWS: Add note about new TLE support on powerpc64le.
diff --git a/NEWS b/NEWS
index 60b15116d63..11d9af739c3 100644
--- a/NEWS
+++ b/NEWS
@@ -39,6 +39,7 @@ The following bugs are resolved with this release:
   [23717] Fix stack overflow in stdlib/tst-setcontext9
   [23821] si_band in siginfo_t has wrong type long int on sparc64
   [23822] ia64 static libm.a is missing exp2f, log2f and powf symbols
+  [23864] libc: [riscv] missing kernel-features.h undefines
   [23844] pthread_rwlock_trywrlock results in hang
   [23927] Linux if_nametoindex() does not close descriptor (CVE-2018-19591)
   [23972] __old_getdents64 uses wrong d_off value on overflow
diff --git a/sysdeps/unix/sysv/linux/riscv/kernel-features.h b/sysdeps/unix/sysv/linux/riscv/kernel-features.h
index 37f4d99a92f..d21c824624f 100644
--- a/sysdeps/unix/sysv/linux/riscv/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/riscv/kernel-features.h
@@ -21,3 +21,8 @@
 
 #undef __ASSUME_CLONE_DEFAULT
 #define __ASSUME_CLONE_BACKWARDS 1
+
+/* No support for PI mutexes or robust futexes before 4.20.  */
+#if __LINUX_KERNEL_VERSION < 0x041400
+# undef __ASSUME_SET_ROBUST_LIST
+#endif
-- 
2.20.1