The patch titled
Fix WARN_ON / WARN_ON_ONCE regression
has been added to the -mm tree. Its filename is
fix-warn_on--warn_on_once-regression.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: Fix WARN_ON / WARN_ON_ONCE regression
From: Andrew Morton <akpm@xxxxxxxx>
Tim and Ananiev report that the recent WARN_ON_ONCE changes cause increased
cache misses with the tbench workload. Apparently due to the access to the
newly-added static variable.
Rearrange the code so that we don't touch that variable unless the warning is
going to trigger.
Also rework the logic so that the static variable starts out at zero, so we
can move it into bss.
It would seem logical to mark the static variable as __read_mostly too. But
it would be wrong, because that would put it back into the vmlinux image, and
the kernel will never read from this variable in normal operation anyway.
Unless the compiler or hardware go and do some prefetching on us?
For some reason this patch shrinks softirq.o text by 40 bytes.
Cc: Tim Chen <tim.c.chen@xxxxxxxxx>
Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Cc: "Ananiev, Leonid I" <leonid.i.ananiev@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
include/asm-generic/bug.h | 16 ++++++++--------
1 files changed, 8 insertions(+), 8 deletions(-)
diff -puN include/asm-generic/bug.h~fix-warn_on--warn_on_once-regression include/asm-generic/bug.h
--- a/include/asm-generic/bug.h~fix-warn_on--warn_on_once-regression
+++ a/include/asm-generic/bug.h
@@ -41,14 +41,14 @@
#endif
#endif
-#define WARN_ON_ONCE(condition) ({ \
- static int __warn_once = 1; \
- typeof(condition) __ret_warn_once = (condition);\
- \
- if (likely(__warn_once)) \
- if (WARN_ON(__ret_warn_once)) \
- __warn_once = 0; \
- unlikely(__ret_warn_once); \
+#define WARN_ON_ONCE(condition) ({ \
+ static int __warned; \
+ typeof(condition) __ret_warn_once = (condition); \
+ \
+ if (unlikely(__ret_warn_once)) \
+ if (WARN_ON(!__warned)) \
+ __warned = 1; \
+ unlikely(__ret_warn_once); \
})
#ifdef CONFIG_SMP
_
Patches currently in -mm which might be from akpm@xxxxxxxx are
kauditd_thread-warning-fix.patch
revert-pci-quirk-for-ibm-dock-ii-cardbus-controllers.patch
fix-warn_on--warn_on_once-regression.patch
git-acpi.patch
acpi-preserve-correct-battery-state-through-suspend-resume-cycles-tidy.patch
acpi-asus-s3-resume-fix.patch
sony_apci-resume.patch
git-cifs-fixup.patch
cifs-kconfig-dont-select-connector.patch
w1-kconfig-fix.patch
git-geode-fixup.patch
git-input-fixup.patch
revert-input-make-input_openclose_device-more-robust.patch
libata-return-sense-data-in-hdio_drive_cmd-ioctl-tidy.patch
forcedeth-power-management-support-tidy.patch
drivers-net-ns83820c-add-paramter-to-disable-auto.patch
git-pcmcia-fixup.patch
git-serial-fixup.patch
pci-optionally-sort-device-lists-breadth-first-tweaks.patch
pci-optionally-sort-device-lists-breadth-first-force-on.patch
git-scsi-target-fixup.patch
git-scsi-target-vs-git-block.patch
xpad-dance-pad-support-tidy.patch
git-watchdog.patch
revert-x86_64-mm-mask-alignment.patch
x86_64-dump_trace-atomicity-fix.patch
spinlock-debug-all-cpu-backtrace.patch
spinlock-debug-all-cpu-backtrace-fix.patch
spinlock-debug-all-cpu-backtrace-fix-2.patch
spinlock-debug-all-cpu-backtrace-fix-3.patch
xfs-rename-uio_read.patch
get-rid-of-zone_table.patch
slab-reduce-numa-text-size-tidy.patch
swap-token-new-scheme-to-preempt-token-tidy.patch
radix-tree-rcu-lockless-readside.patch
acx1xx-wireless-driver.patch
swsusp-add-resume_offset-command-line-parameter-rev-2.patch
deprecate-smbfs-in-favour-of-cifs.patch
edac-new-opteron-athlon64-memory-controller-driver.patch
add-address_space_operationsbatch_write.patch
add-config_headers_check-option-to-automatically-run-make-headers_check-nobble.patch
kbuild-dont-put-temp-files-in-the-source-tree.patch
grow_buffers-infinite-loop-fix.patch
generic-implementatation-of-bug.patch
generic-implementatation-of-bug-fix.patch
generic-bug-for-i386.patch
generic-bug-for-x86-64.patch
fs-cache-make-kafs-use-fs-cache-fix.patch
fs-cache-make-kafs-use-fs-cache-vs-streamline-generic_file_-interfaces-and-filemap.patch
nfs-use-local-caching-12-fix.patch
swap_prefetch-vs-zoned-counters.patch
readahead-sysctl-parameters.patch
make-copy_from_user_inatomic-not-zero-the-tail-on-i386-vs-reiser4.patch
make-kmem_cache_destroy-return-void-reiser4.patch
reiser4-hardirq-include-fix.patch
reiser4-run-truncate_inode_pages-in-reiser4_delete_inode.patch
reiser4-get_sb_dev-fix.patch
reiser4-vs-zoned-allocator.patch
reiser4-rename-generic_sounding_globalspatch-fix.patch
hpt3xx-rework-rate-filtering-tidy.patch
kevent-core-files-fix.patch
kevent-core-files-s390-hack.patch
kevent-socket-notifications-fix-2.patch
kevent-socket-notifications-fix-4.patch
nr_blockdev_pages-in_interrupt-warning.patch
device-suspend-debug.patch
slab-leaks3-default-y.patch
x86-kmap_atomic-debugging.patch
restore-rogue-readahead-printk.patch
put_bh-debug.patch
acpi_format_exception-debug.patch
jmicron-warning-fix.patch
squash-ipc-warnings.patch
squash-transmeta-warnings.patch
squash-udf-warnings.patch
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