commit e96ebd589debd9a6a793608c4ec7019c38785dea upstream.
This patch implements the __smp_store_release and __smp_load_acquire barriers
using ordered stores and loads. This avoids the sync instruction present in
the generic implementation.
Cc: <stable@vger.kernel.org> # 4.14+
Signed-off-by: Dave Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 6e9f06ee6c9566f3606d93182ac8f803a148504b upstream.
This reverts commit 9e5c602186a692a7e848c0da17aed40f49d30519.
No need to use the ldcw instruction as SMP spinlock release barrier.
Revert it to gain back speed again.
Signed-off-by: Helge Deller <deller@gmx.de>
Cc: <stable@vger.kernel.org> # v5.2+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit b344d6a83d01c52fddbefa6b3b4764da5b1022a0 ]
The kernel test bot reported[1] that using set_mask_bits on a u8 causes
the following issue on parisc:
hppa-linux-ld: drivers/phy/ti/phy-tusb1210.o: in function `tusb1210_probe':
>> (.text+0x2f4): undefined reference to `__cmpxchg_called_with_bad_pointer'
>> hppa-linux-ld: (.text+0x324): undefined reference to `__cmpxchg_called_with_bad_pointer'
hppa-linux-ld: (.text+0x354): undefined reference to `__cmpxchg_called_with_bad_pointer'
Add support for cmpxchg on u8 pointers.
[1] https://lore.kernel.org/patchwork/patch/1272617/#1468946
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Liam Beguin <liambeguin@gmail.com>
Tested-by: Dave Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit be6577af0cef934ccb036445314072e8cb9217b9 upstream.
Stalls are quite frequent with recent kernels. I enabled
CONFIG_SOFTLOCKUP_DETECTOR and I caught the following stall:
watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [cc1:22803]
CPU: 0 PID: 22803 Comm: cc1 Not tainted 5.6.17+ #3
Hardware name: 9000/800/rp3440
IAOQ[0]: d_alloc_parallel+0x384/0x688
IAOQ[1]: d_alloc_parallel+0x388/0x688
RP(r2): d_alloc_parallel+0x134/0x688
Backtrace:
[<000000004036974c>] __lookup_slow+0xa4/0x200
[<0000000040369fc8>] walk_component+0x288/0x458
[<000000004036a9a0>] path_lookupat+0x88/0x198
[<000000004036e748>] filename_lookup+0xa0/0x168
[<000000004036e95c>] user_path_at_empty+0x64/0x80
[<000000004035d93c>] vfs_statx+0x104/0x158
[<000000004035dfcc>] __do_sys_lstat64+0x44/0x80
[<000000004035e5a0>] sys_lstat64+0x20/0x38
[<0000000040180054>] syscall_exit+0x0/0x14
The code was stuck in this loop in d_alloc_parallel:
4037d414: 0e 00 10 dc ldd 0(r16),ret0
4037d418: c7 fc 5f ed bb,< ret0,1f,4037d414 <d_alloc_parallel+0x384>
4037d41c: 08 00 02 40 nop
This is the inner loop of bit_spin_lock which is called by hlist_bl_unlock in
d_alloc_parallel:
static inline void bit_spin_lock(int bitnum, unsigned long *addr)
{
/*
* Assuming the lock is uncontended, this never enters
* the body of the outer loop. If it is contended, then
* within the inner loop a non-atomic test is used to
* busywait with less bus contention for a good time to
* attempt to acquire the lock bit.
*/
preempt_disable();
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
while (unlikely(test_and_set_bit_lock(bitnum, addr))) {
preempt_enable();
do {
cpu_relax();
} while (test_bit(bitnum, addr));
preempt_disable();
}
#endif
__acquire(bitlock);
}
After consideration, I realized that we must be losing bit unlocks.
Then, I noticed that we missed defining atomic64_set_release().
Adding this define fixes the stalls in bit operations.
Signed-off-by: Dave Anglin <dave.anglin@bell.net>
Cc: stable@vger.kernel.org
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Gao Xiang