diff options
Diffstat (limited to 'linux-5.3-compat-retire-rw_tryupgrade.patch')
| -rw-r--r-- | linux-5.3-compat-retire-rw_tryupgrade.patch | 236 |
1 files changed, 0 insertions, 236 deletions
diff --git a/linux-5.3-compat-retire-rw_tryupgrade.patch b/linux-5.3-compat-retire-rw_tryupgrade.patch deleted file mode 100644 index 253c35868b7e..000000000000 --- a/linux-5.3-compat-retire-rw_tryupgrade.patch +++ /dev/null @@ -1,236 +0,0 @@ -From ee1848356f32e31f001ca96cc68e06a445f72108 Mon Sep 17 00:00:00 2001 -From: Brian Behlendorf <behlendorf1@llnl.gov> -Date: Fri, 12 Jul 2019 14:06:36 -0700 -Subject: [PATCH] Linux 5.3 compat: retire rw_tryupgrade() - -The Linux kernel's rwsem's have never provided an interface to -allow a reader to be upgraded to a writer. Historically, this -functionality has been implemented by a SPL wrapper function. -However, this approach depends on internal knowledge of the -rw_semaphore and is therefore rather brittle. - -Since the ZFS code must always be able to fallback to rw_exit() -and rw_enter() when an rw_tryupgrade() fails; this functionality -isn't critical. Furthermore, the only potentially performance -sensitive consumer is dmu_zfetch() and no decrease in performance -was observed with this change applied. See the PR comments for -additional testing details. - -Therefore, it is being retired to make the build more robust and -to simplify the rwlock implementation. - -Reviewed-by: Tony Hutter <hutter2@llnl.gov> -Reviewed-by: Tomohiro Kusumi <kusumi.tomohiro@gmail.com> -Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> -Closes #9029 ---- - include/spl/sys/rwlock.h | 60 +++-------------------- - module/spl/spl-rwlock.c | 101 --------------------------------------- - 2 files changed, 7 insertions(+), 154 deletions(-) - -diff --git a/include/spl/sys/rwlock.h b/include/spl/sys/rwlock.h -index 5e052b532a4..89e02fa8f04 100644 ---- a/include/spl/sys/rwlock.h -+++ b/include/spl/sys/rwlock.h -@@ -29,43 +29,6 @@ - #include <linux/rwsem.h> - #include <linux/sched.h> - --/* Linux kernel compatibility */ --#if defined(CONFIG_PREEMPT_RT_FULL) --#define SPL_RWSEM_SINGLE_READER_VALUE (1) --#define SPL_RWSEM_SINGLE_WRITER_VALUE (0) --#elif defined(CONFIG_RWSEM_GENERIC_SPINLOCK) --#define SPL_RWSEM_SINGLE_READER_VALUE (1) --#define SPL_RWSEM_SINGLE_WRITER_VALUE (-1) --#elif defined(RWSEM_ACTIVE_MASK) --#define SPL_RWSEM_SINGLE_READER_VALUE (RWSEM_ACTIVE_READ_BIAS) --#define SPL_RWSEM_SINGLE_WRITER_VALUE (RWSEM_ACTIVE_WRITE_BIAS) --#endif -- --/* Linux 3.16 changed activity to count for rwsem-spinlock */ --#if defined(CONFIG_PREEMPT_RT_FULL) --#define RWSEM_COUNT(sem) sem->read_depth --#elif defined(HAVE_RWSEM_ACTIVITY) --#define RWSEM_COUNT(sem) sem->activity --/* Linux 4.8 changed count to an atomic_long_t for !rwsem-spinlock */ --#elif defined(HAVE_RWSEM_ATOMIC_LONG_COUNT) --#define RWSEM_COUNT(sem) atomic_long_read(&(sem)->count) --#else --#define RWSEM_COUNT(sem) sem->count --#endif -- --#if defined(RWSEM_SPINLOCK_IS_RAW) --#define spl_rwsem_lock_irqsave(lk, fl) raw_spin_lock_irqsave(lk, fl) --#define spl_rwsem_unlock_irqrestore(lk, fl) \ -- raw_spin_unlock_irqrestore(lk, fl) --#define spl_rwsem_trylock_irqsave(lk, fl) raw_spin_trylock_irqsave(lk, fl) --#else --#define spl_rwsem_lock_irqsave(lk, fl) spin_lock_irqsave(lk, fl) --#define spl_rwsem_unlock_irqrestore(lk, fl) spin_unlock_irqrestore(lk, fl) --#define spl_rwsem_trylock_irqsave(lk, fl) spin_trylock_irqsave(lk, fl) --#endif /* RWSEM_SPINLOCK_IS_RAW */ -- --#define spl_rwsem_is_locked(rwsem) rwsem_is_locked(rwsem) -- - typedef enum { - RW_DRIVER = 2, - RW_DEFAULT = 4, -@@ -133,7 +96,7 @@ spl_rw_lockdep_on_maybe(krwlock_t *rwp) \ - static inline int - RW_LOCK_HELD(krwlock_t *rwp) - { -- return (spl_rwsem_is_locked(SEM(rwp))); -+ return (rwsem_is_locked(SEM(rwp))); - } - - static inline int -@@ -170,6 +133,12 @@ RW_READ_HELD(krwlock_t *rwp) - */ - #define rw_destroy(rwp) ((void) 0) - -+/* -+ * Upgrading a rwsem from a reader to a writer is not supported by the -+ * Linux kernel. The lock must be dropped and reacquired as a writer. -+ */ -+#define rw_tryupgrade(rwp) RW_WRITE_HELD(rwp) -+ - #define rw_tryenter(rwp, rw) \ - ({ \ - int _rc_ = 0; \ -@@ -228,24 +197,9 @@ RW_READ_HELD(krwlock_t *rwp) - spl_rw_lockdep_on_maybe(rwp); \ - }) - --#define rw_tryupgrade(rwp) \ --({ \ -- int _rc_ = 0; \ -- \ -- if (RW_WRITE_HELD(rwp)) { \ -- _rc_ = 1; \ -- } else { \ -- spl_rw_lockdep_off_maybe(rwp); \ -- if ((_rc_ = rwsem_tryupgrade(SEM(rwp)))) \ -- spl_rw_set_owner(rwp); \ -- spl_rw_lockdep_on_maybe(rwp); \ -- } \ -- _rc_; \ --}) - /* END CSTYLED */ - - int spl_rw_init(void); - void spl_rw_fini(void); --int rwsem_tryupgrade(struct rw_semaphore *rwsem); - - #endif /* _SPL_RWLOCK_H */ -diff --git a/module/spl/spl-rwlock.c b/module/spl/spl-rwlock.c -index 886e16924e6..10f7c38db4e 100644 ---- a/module/spl/spl-rwlock.c -+++ b/module/spl/spl-rwlock.c -@@ -24,106 +24,5 @@ - * Solaris Porting Layer (SPL) Reader/Writer Lock Implementation. - */ - --#include <sys/rwlock.h> --#include <linux/module.h> -- --#if defined(CONFIG_PREEMPT_RT_FULL) -- --#include <linux/rtmutex.h> --#define RT_MUTEX_OWNER_MASKALL 1UL -- --static int --__rwsem_tryupgrade(struct rw_semaphore *rwsem) --{ --#if defined(READER_BIAS) && defined(WRITER_BIAS) -- /* -- * After the 4.9.20-rt16 kernel the realtime patch series lifted the -- * single reader restriction. While this could be accommodated by -- * adding additional compatibility code assume the rwsem can never -- * be upgraded. All caller must already cleanly handle this case. -- */ -- return (0); --#else -- ASSERT((struct task_struct *) -- ((unsigned long)rwsem->lock.owner & ~RT_MUTEX_OWNER_MASKALL) == -- current); -- -- /* -- * Prior to 4.9.20-rt16 kernel the realtime patch series, rwsem is -- * implemented as a single mutex held by readers and writers alike. -- * However, this implementation would prevent a thread from taking -- * a read lock twice, as the mutex would already be locked on -- * the second attempt. Therefore the implementation allows a -- * single thread to take a rwsem as read lock multiple times -- * tracking that nesting as read_depth counter. -- */ -- if (rwsem->read_depth <= 1) { -- /* -- * In case, the current thread has not taken the lock -- * more than once as read lock, we can allow an -- * upgrade to a write lock. rwsem_rt.h implements -- * write locks as read_depth == 0. -- */ -- rwsem->read_depth = 0; -- return (1); -- } -- return (0); --#endif --} --#elif defined(CONFIG_RWSEM_GENERIC_SPINLOCK) --static int --__rwsem_tryupgrade(struct rw_semaphore *rwsem) --{ -- int ret = 0; -- unsigned long flags; -- spl_rwsem_lock_irqsave(&rwsem->wait_lock, flags); -- if (RWSEM_COUNT(rwsem) == SPL_RWSEM_SINGLE_READER_VALUE && -- list_empty(&rwsem->wait_list)) { -- ret = 1; -- RWSEM_COUNT(rwsem) = SPL_RWSEM_SINGLE_WRITER_VALUE; -- } -- spl_rwsem_unlock_irqrestore(&rwsem->wait_lock, flags); -- return (ret); --} --#elif defined(RWSEM_ACTIVE_MASK) --#if defined(HAVE_RWSEM_ATOMIC_LONG_COUNT) --static int --__rwsem_tryupgrade(struct rw_semaphore *rwsem) --{ -- long val; -- val = atomic_long_cmpxchg(&rwsem->count, SPL_RWSEM_SINGLE_READER_VALUE, -- SPL_RWSEM_SINGLE_WRITER_VALUE); -- return (val == SPL_RWSEM_SINGLE_READER_VALUE); --} --#else --static int --__rwsem_tryupgrade(struct rw_semaphore *rwsem) --{ -- typeof(rwsem->count) val; -- val = cmpxchg(&rwsem->count, SPL_RWSEM_SINGLE_READER_VALUE, -- SPL_RWSEM_SINGLE_WRITER_VALUE); -- return (val == SPL_RWSEM_SINGLE_READER_VALUE); --} --#endif --#else --static int --__rwsem_tryupgrade(struct rw_semaphore *rwsem) --{ -- return (0); --} --#endif -- --int --rwsem_tryupgrade(struct rw_semaphore *rwsem) --{ -- if (__rwsem_tryupgrade(rwsem)) { -- rwsem_release(&rwsem->dep_map, 1, _RET_IP_); -- rwsem_acquire(&rwsem->dep_map, 0, 1, _RET_IP_); -- return (1); -- } -- return (0); --} --EXPORT_SYMBOL(rwsem_tryupgrade); -- - int spl_rw_init(void) { return 0; } - void spl_rw_fini(void) { } |