From 268265d6c93d82f682b52b96ca21e22c32a4b6db Mon Sep 17 00:00:00 2001 From: Mike Galbraith Date: Thu, 31 Mar 2016 04:08:28 +0200 Subject: [PATCH 17/64] zram: Replace bit spinlocks with spinlock_t for PREEMPT_RT. Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.1/older/patches-6.1.82-rt27.tar.xz The bit spinlock disables preemption on PREEMPT_RT. With disabled preemption it is not allowed to acquire other sleeping locks which includes invoking zs_free(). Use a spinlock_t on PREEMPT_RT for locking and set/ clear ZRAM_LOCK after the lock has been acquired/ dropped. Signed-off-by: Mike Galbraith Signed-off-by: Sebastian Andrzej Siewior Link: https://lkml.kernel.org/r/YqIbMuHCPiQk+Ac2@linutronix.de --- drivers/block/zram/zram_drv.c | 36 +++++++++++++++++++++++++++++++++++ drivers/block/zram/zram_drv.h | 3 +++ 2 files changed, 39 insertions(+) diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 966aab902d19..ee69e4443691 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -57,6 +57,40 @@ static void zram_free_page(struct zram *zram, size_t index); static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec, u32 index, int offset, struct bio *bio); +#ifdef CONFIG_PREEMPT_RT +static void zram_meta_init_table_locks(struct zram *zram, size_t num_pages) +{ + size_t index; + + for (index = 0; index < num_pages; index++) + spin_lock_init(&zram->table[index].lock); +} + +static int zram_slot_trylock(struct zram *zram, u32 index) +{ + int ret; + + ret = spin_trylock(&zram->table[index].lock); + if (ret) + __set_bit(ZRAM_LOCK, &zram->table[index].flags); + return ret; +} + +static void zram_slot_lock(struct zram *zram, u32 index) +{ + spin_lock(&zram->table[index].lock); + __set_bit(ZRAM_LOCK, &zram->table[index].flags); +} + +static void zram_slot_unlock(struct zram *zram, u32 index) +{ + __clear_bit(ZRAM_LOCK, &zram->table[index].flags); + spin_unlock(&zram->table[index].lock); +} + +#else + +static void zram_meta_init_table_locks(struct zram *zram, size_t num_pages) { } static int zram_slot_trylock(struct zram *zram, u32 index) { @@ -72,6 +106,7 @@ static void zram_slot_unlock(struct zram *zram, u32 index) { bit_spin_unlock(ZRAM_LOCK, &zram->table[index].flags); } +#endif static inline bool init_done(struct zram *zram) { @@ -1187,6 +1222,7 @@ static bool zram_meta_alloc(struct zram *zram, u64 disksize) if (!huge_class_size) huge_class_size = zs_huge_class_size(zram->mem_pool); + zram_meta_init_table_locks(zram, num_pages); return true; } diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h index a2bda53020fd..ae7950b26db5 100644 --- a/drivers/block/zram/zram_drv.h +++ b/drivers/block/zram/zram_drv.h @@ -62,6 +62,9 @@ struct zram_table_entry { unsigned long element; }; unsigned long flags; +#ifdef CONFIG_PREEMPT_RT + spinlock_t lock; +#endif #ifdef CONFIG_ZRAM_MEMORY_TRACKING ktime_t ac_time; #endif -- 2.44.0