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authorPaul Murphy <murphyp@linux.vnet.ibm.com>2015-08-27 09:48:04 -0500
committerTulio Magno Quites Machado Filho <tuliom@linux.vnet.ibm.com>2015-10-27 17:27:41 -0200
commit72f1463df85a522bfd1568e47bd81371522ee358 (patch)
treea257dcbec150b619574c29326f89ee10d013891f
parent76c5ae00284d98f1994434c570bdcde9dbc6b49e (diff)
downloadglibc-72f1463df85a522bfd1568e47bd81371522ee358.tar.gz
powerpc: Fix usage of elision transient failure adapt param
The skip_lock_out_of_tbegin_retries adaptive parameter was not being used correctly, nor as described. This prevents a fallback for all users of the lock if a transient abort occurs within the accepted number of retries. [BZ #19174] * sysdeps/powerpc/nptl/elide.h (__elide_lock): Fix usage of .skip_lock_out_of_tbegin_retries. * sysdeps/unix/sysv/linux/powerpc/elision-lock.c (__lll_lock_elision): Likewise, and respect a value of try_tbegin <= 0.
-rw-r--r--ChangeLog9
-rw-r--r--NEWS2
-rw-r--r--sysdeps/powerpc/nptl/elide.h6
-rw-r--r--sysdeps/unix/sysv/linux/powerpc/elision-lock.c15
4 files changed, 19 insertions, 13 deletions
diff --git a/ChangeLog b/ChangeLog
index a392a75030..0a70fee964 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2015-10-27 Paul E. Murphy <murphyp@linux.vnet.ibm.com>
+
+ [BZ #19174]
+ * sysdeps/powerpc/nptl/elide.h (__elide_lock): Fix usage of
+ .skip_lock_out_of_tbegin_retries.
+ * sysdeps/unix/sysv/linux/powerpc/elision-lock.c
+ (__lll_lock_elision): Likewise, and respect a value of
+ try_tbegin <= 0.
+
2015-10-27 Carlos Eduardo Seo <cseo@linux.vnet.ibm.com>
* elf/dl-support.c (_dl_aux_init): Added AT_PLATFORM to the case
diff --git a/NEWS b/NEWS
index 1122affd0d..5120ddc24d 100644
--- a/NEWS
+++ b/NEWS
@@ -21,7 +21,7 @@ Version 2.23
18970, 18977, 18980, 18981, 18982, 18985, 19003, 19007, 19012, 19016,
19018, 19032, 19046, 19049, 19050, 19059, 19071, 19074, 19076, 19077,
19078, 19079, 19085, 19086, 19088, 19094, 19095, 19124, 19125, 19129,
- 19134, 19137, 19156.
+ 19134, 19137, 19156, 19174.
* There is now a --disable-timezone-tools configure option for disabling the
building and installing of the timezone related utilities (zic, zdump, and
diff --git a/sysdeps/powerpc/nptl/elide.h b/sysdeps/powerpc/nptl/elide.h
index 12171f45dc..2e1e443278 100644
--- a/sysdeps/powerpc/nptl/elide.h
+++ b/sysdeps/powerpc/nptl/elide.h
@@ -27,7 +27,7 @@
configurations. Returns true if the system should retry again or false
otherwise. */
static inline bool
-__get_new_count (uint8_t *adapt_count)
+__get_new_count (uint8_t *adapt_count, int attempt)
{
/* A persistent failure indicates that a retry will probably
result in another failure. Use normal locking now and
@@ -40,7 +40,7 @@ __get_new_count (uint8_t *adapt_count)
}
/* Same logic as above, but for a number of temporary failures in a
a row. */
- else if (__elision_aconf.skip_lock_out_of_tbegin_retries > 0
+ else if (attempt <= 1 && __elision_aconf.skip_lock_out_of_tbegin_retries > 0
&& __elision_aconf.try_tbegin > 0)
*adapt_count = __elision_aconf.skip_lock_out_of_tbegin_retries;
return true;
@@ -78,7 +78,7 @@ __get_new_count (uint8_t *adapt_count)
__builtin_tabort (_ABORT_LOCK_BUSY); \
} \
else \
- if (!__get_new_count(&adapt_count)) \
+ if (!__get_new_count (&adapt_count,i)) \
break; \
} \
ret; \
diff --git a/sysdeps/unix/sysv/linux/powerpc/elision-lock.c b/sysdeps/unix/sysv/linux/powerpc/elision-lock.c
index 3762732379..4775fcad10 100644
--- a/sysdeps/unix/sysv/linux/powerpc/elision-lock.c
+++ b/sysdeps/unix/sysv/linux/powerpc/elision-lock.c
@@ -50,8 +50,7 @@ __lll_lock_elision (int *lock, short *adapt_count, EXTRAARG int pshared)
goto use_lock;
}
- int try_begin = aconf.try_tbegin;
- while (1)
+ for (int i = aconf.try_tbegin; i > 0; i--)
{
if (__builtin_tbegin (0))
{
@@ -65,21 +64,19 @@ __lll_lock_elision (int *lock, short *adapt_count, EXTRAARG int pshared)
/* A persistent failure indicates that a retry will probably
result in another failure. Use normal locking now and
for the next couple of calls. */
- if (try_begin-- <= 0
- || _TEXASRU_FAILURE_PERSISTENT (__builtin_get_texasru ()))
+ if (_TEXASRU_FAILURE_PERSISTENT (__builtin_get_texasru ()))
{
if (aconf.skip_lock_internal_abort > 0)
*adapt_count = aconf.skip_lock_internal_abort;
goto use_lock;
}
- /* Same logic as above, but for for a number of temporary failures
- in a row. */
- else if (aconf.skip_lock_out_of_tbegin_retries > 0
- && aconf.try_tbegin > 0)
- *adapt_count = aconf.skip_lock_out_of_tbegin_retries;
}
}
+ /* Fall back to locks for a bit if retries have been exhausted */
+ if (aconf.try_tbegin > 0 && aconf.skip_lock_out_of_tbegin_retries > 0)
+ *adapt_count = aconf.skip_lock_out_of_tbegin_retries;
+
use_lock:
return LLL_LOCK ((*lock), pshared);
}