kernel.git/arch/parisc/include/asm/spinlock.h, branch linux-5.8.y

Revert "parisc: Revert "Release spinlocks using ordered store""

2020-08-19T06:27:07Z

commit 157e9afcc4fa25068b0e8743bc254a9b56010e13 upstream. This reverts commit 86d4d068df573a8c2105554624796c086d6bec3d. Signed-off-by: Helge Deller Cc: # v5.0+ Signed-off-by: Greg Kroah-Hartman

Revert "parisc: Use ldcw instruction for SMP spinlock release barrier"

2020-08-19T06:27:07Z

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 Cc: # v5.2+ Signed-off-by: Greg Kroah-Hartman

Revert "parisc: Improve interrupt handling in arch_spin_lock_flags()"

2020-08-19T06:27:06Z

commit 3d05b8aebc5f10ee3ab129b61100196855dd7249 upstream. This reverts commit 2772f0efd5bbd5413db3d22e363b779ca0fa5310. It turns out that we want to implement the spinlock code differently. Signed-off-by: Helge Deller Cc: # v5.7+ Signed-off-by: Greg Kroah-Hartman

parisc: Rework arch_rw locking functions

2020-04-05T20:29:55Z

Clean up the arch read/write locking functions based on the arc implemenation. This improves readability of those functions. Signed-off-by: Helge Deller

parisc: Improve interrupt handling in arch_spin_lock_flags()

2020-04-05T20:16:38Z

Rewrite arch_spin_lock() and arch_spin_lock_flags() to not re-enable and disable the PSW_SM_I interrupt flag too often. Signed-off-by: Helge Deller

parisc: Use ldcw instruction for SMP spinlock release barrier

2019-05-03T21:47:40Z

There are only a couple of instructions that can function as a memory barrier on parisc. Currently, we use the sync instruction as a memory barrier when releasing a spinlock. However, the ldcw instruction is a better barrier when we have a handy memory location since it operates in the cache on coherent machines. This patch updates the spinlock release code to use ldcw. I also changed the "stw,ma" instructions to "stw" instructions as it is not an adequate barrier. Signed-off-by: John David Anglin Signed-off-by: Helge Deller

parisc: Revert "Release spinlocks using ordered store"

2018-11-06T11:03:22Z

This reverts commit d27dfa13b9f77ae7e6ed09d70a0426ed26c1a8f9. Unfortunately, this patch needs to be reverted. We need the full sync barrier and not the limited barrier provided by using an ordered store. The sync ensures that all accesses and cache purge instructions that follow the sync are performed after all such instructions prior the sync instruction have completed executing. The patch breaks the rwlock implementation in glibc. This caused the test-lock application in the libprelude testsuite to hang. With the change reverted, the test runs correctly and the libprelude package builds successfully. Signed-off-by: John David Anglin Signed-off-by: Helge Deller

parisc: Release spinlocks using ordered store

2018-10-17T06:18:01Z

This patch updates the spin unlock code to use an ordered store with release semanatics. All prior accesses are guaranteed to be performed before an ordered store is performed. Using an ordered store is significantly faster than using the sync memory barrier. Signed-off-by: John David Anglin Signed-off-by: Helge Deller

parisc: Remove unnecessary barriers from spinlock.h

2018-08-13T07:31:25Z

Now that mb() is an instruction barrier, it will slow performance if we issue unnecessary barriers. The spinlock defines have a number of unnecessary barriers. The __ldcw() define is both a hardware and compiler barrier. The mb() barriers in the routines using __ldcw() serve no purpose. The only barrier needed is the one in arch_spin_unlock(). We need to ensure all accesses are complete prior to releasing the lock. Signed-off-by: John David Anglin Cc: stable@vger.kernel.org # 4.0+ Signed-off-by: Helge Deller

Merge branch 'linus' into locking/core, to resolve conflicts

2017-11-07T09:32:44Z

Conflicts: include/linux/compiler-clang.h include/linux/compiler-gcc.h include/linux/compiler-intel.h include/uapi/linux/stddef.h Signed-off-by: Ingo Molnar