The patch titled
kexec: use a spinlock for locking rather than xchg()
has been added to the -mm tree. Its filename is
kexec-use-a-bitop-for-locking-rather-than-xchg.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: kexec: use a spinlock for locking rather than xchg()
From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Functionally the same, but more conventional.
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/kexec.c | 30 ++++++++----------------------
1 file changed, 8 insertions(+), 22 deletions(-)
diff -puN kernel/kexec.c~kexec-use-a-bitop-for-locking-rather-than-xchg kernel/kexec.c
--- a/kernel/kexec.c~kexec-use-a-bitop-for-locking-rather-than-xchg
+++ a/kernel/kexec.c
@@ -924,19 +924,14 @@ static int kimage_load_segment(struct ki
*/
struct kimage *kexec_image;
struct kimage *kexec_crash_image;
-/*
- * A home grown binary mutex.
- * Nothing can wait so this mutex is safe to use
- * in interrupt context :)
- */
-static int kexec_lock;
+
+static DEFINE_SPINLOCK(kexec_lock);
asmlinkage long sys_kexec_load(unsigned long entry, unsigned long nr_segments,
struct kexec_segment __user *segments,
unsigned long flags)
{
struct kimage **dest_image, *image;
- int locked;
int result;
/* We only trust the superuser with rebooting the system. */
@@ -972,8 +967,7 @@ asmlinkage long sys_kexec_load(unsigned
*
* KISS: always take the mutex.
*/
- locked = xchg(&kexec_lock, 1);
- if (locked)
+ if (!spin_trylock(&kexec_lock))
return -EBUSY;
dest_image = &kexec_image;
@@ -1015,8 +1009,7 @@ asmlinkage long sys_kexec_load(unsigned
image = xchg(dest_image, image);
out:
- locked = xchg(&kexec_lock, 0); /* Release the mutex */
- BUG_ON(!locked);
+ spin_unlock(&kexec_lock);
kimage_free(image);
return result;
@@ -1063,9 +1056,6 @@ asmlinkage long compat_sys_kexec_load(un
void crash_kexec(struct pt_regs *regs)
{
- int locked;
-
-
/* Take the kexec_lock here to prevent sys_kexec_load
* running on one cpu from replacing the crash kernel
* we are using after a panic on a different cpu.
@@ -1074,8 +1064,7 @@ void crash_kexec(struct pt_regs *regs)
* of memory the xchg(&kexec_crash_image) would be
* sufficient. But since I reuse the memory...
*/
- locked = xchg(&kexec_lock, 1);
- if (!locked) {
+ if (spin_trylock(&kexec_lock)) {
if (kexec_crash_image) {
struct pt_regs fixed_regs;
crash_setup_regs(&fixed_regs, regs);
@@ -1083,8 +1072,7 @@ void crash_kexec(struct pt_regs *regs)
machine_crash_shutdown(&fixed_regs);
machine_kexec(kexec_crash_image);
}
- locked = xchg(&kexec_lock, 0);
- BUG_ON(!locked);
+ spin_unlock(&kexec_lock);
}
}
@@ -1434,7 +1422,7 @@ int kernel_kexec(void)
{
int error = 0;
- if (xchg(&kexec_lock, 1))
+ if (!spin_trylock(&kexec_lock))
return -EBUSY;
if (!kexec_image) {
error = -EINVAL;
@@ -1498,8 +1486,6 @@ int kernel_kexec(void)
#endif
Unlock:
- if (!xchg(&kexec_lock, 0))
- BUG();
-
+ spin_unlock(&kexec_lock);
return error;
}
_
Patches currently in -mm which might be from akpm@xxxxxxxxxxxxxxxxxxxx are
seq_file-fix-bug-when-seq_read-reads-nothing.patch
linux-next.patch
next-remove-localversion.patch
acpi-trivial-cleanups-fix.patch
arch-x86-pci-irqc-attempt-to-clean-up-code-layout.patch
zero-based-percpu-use-vmlinux_symbol-in-include-asm-generic-vmlinuxldsh.patch
ppc-use-the-common-ascii-hex-helpers.patch
powerpc-replace-__function__-with-__func__.patch
tick-schedc-suppress-needless-timer-reprogramming.patch
git-jg-misc.patch
drivers-ata-pata_it821xc-fix-warning.patch
git-ubi-git-rejects.patch
sundance-set-carrier-status-on-link-change-events.patch
cassini-use-request_firmware.patch
e1000e-remove-inapplicable-test-for-ioport-checkpatch-fixes.patch
backlight-driver-for-tabletkiosk-sahara-touchit-213-tablet-pc-checkpatch-fixes.patch
ftrace-printk-formatting-infrastructure-fix-fix.patch
scsi-gdthc-use-unaligned-access-helpers.patch
git-xtensa.patch
kexec-jump-check-code-size-in-control-page-fix.patch
kexec-use-a-bitop-for-locking-rather-than-xchg.patch
scsi-dpt_i2o-is-bust-on-ia64.patch
hwmon-adc124s501-generic-driver.patch
rcu-fix-synchronize_rcu-so-that-kernel-doc-works.patch
ftrace-disable-function-tracing-bringing-up-new-cpu.patch
scsi-megaraid_sas-add-the-new-controllers-support.patch
unrevert-usb-dont-explicitly-reenable-root-hub-status-interrupts.patch
vmscan-give-referenced-active-and-unmapped-pages-a-second-trip-around-the-lru.patch
vm-dont-run-touch_buffer-during-buffercache-lookups.patch
vmscan-move-isolate_lru_page-to-vmscanc.patch
define-page_file_cache-function.patch
vmscan-split-lru-lists-into-anon-file-sets.patch
unevictable-lru-infrastructure.patch
unevictable-lru-page-statistics.patch
mlock-mlocked-pages-are-unevictable.patch
mmap-handle-mlocked-pages-during-map-remap-unmap.patch
vmscan-unevictable-lru-scan-sysctl.patch
h8300-generic_bug-support-checkpatch-fixes.patch
container-freezer-implement-freezer-cgroup-subsystem-checkpatch-fixes.patch
autofs4-track-uid-and-gid-of-last-mount-requester-fix.patch
autofs4-add-miscellaneous-device-for-ioctls-fix.patch
autofs4-add-miscellaneous-device-for-ioctls-fix-2.patch
autofs4-add-miscellaneous-device-for-ioctls-fix-fix-3.patch
rtc-add-device-driver-for-dallas-ds3234-spi-rtc-chip-fix.patch
fb-push-down-the-bkl-in-the-ioctl-handler-checkpatch-fixes.patch
viafb-viafbmodes-viafbtxt-fix-fix.patch
viafb-accelc-accelh-checkpatch-fixes.patch
viafb-dvic-dvih-globalc-and-globalh-checkpatch-fixes.patch
viafb-hwc-hwh-checkpatch-fixes.patch
viafb-viafbdevc-viafbdevh-checkpatch-fixes.patch
fbdev-kconfig-update-fix.patch
eink_apollofb-new-driver-for-apollo-eink-controller.patch
gcov-architecture-specific-compile-flag-adjustments-powerpc-moved-stuff.patch
net-tipc-subscrc-dont-use-___constant_swab32.patch
reiser4.patch
reiser4-tree_lock-fixes.patch
reiser4-tree_lock-fixes-fix.patch
reiser4-semaphore-fix.patch
slb-drop-kmem-cache-argument-from-constructor-reiser4.patch
reiser4-suid.patch
reiser4-track-upstream-changes.patch
page-owner-tracking-leak-detector.patch
nr_blockdev_pages-in_interrupt-warning.patch
slab-leaks3-default-y.patch
put_bh-debug.patch
shrink_slab-handle-bad-shrinkers.patch
getblk-handle-2tb-devices.patch
getblk-handle-2tb-devices-fix.patch
undeprecate-pci_find_device.patch
notify_change-callers-must-hold-i_mutex.patch
profile-likely-unlikely-macros.patch
drivers-net-bonding-bond_sysfsc-suppress-uninitialized-var-warning.patch
w1-build-fix.patch
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