From cdff10ec863d6d0e7d18beb8cb66adc86674bb2b Mon Sep 17 00:00:00 2001 From: Mike Galbraith Date: Thu, 31 Mar 2016 04:08:28 +0200 Subject: [PATCH 246/347] drivers/block/zram: Replace bit spinlocks with rtmutex for -rt Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.246-rt110.tar.xz They're nondeterministic, and lead to ___might_sleep() splats in -rt. OTOH, they're a lot less wasteful than an rtmutex per page. Signed-off-by: Mike Galbraith Signed-off-by: Sebastian Andrzej Siewior --- drivers/block/zram/zram_drv.c | 38 +++++++++++++++++++++++++++++++++++ drivers/block/zram/zram_drv.h | 3 +++ 2 files changed, 41 insertions(+) diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 5e05bfcecd7b..04e4297f8318 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -53,6 +53,40 @@ static size_t huge_class_size; static void zram_free_page(struct zram *zram, size_t index); +#ifdef CONFIG_PREEMPT_RT_BASE +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].value); + 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].value); +} + +static void zram_slot_unlock(struct zram *zram, u32 index) +{ + __clear_bit(ZRAM_LOCK, &zram->table[index].value); + 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) { return bit_spin_trylock(ZRAM_LOCK, &zram->table[index].value); @@ -67,6 +101,7 @@ static void zram_slot_unlock(struct zram *zram, u32 index) { bit_spin_unlock(ZRAM_LOCK, &zram->table[index].value); } +#endif static inline bool init_done(struct zram *zram) { @@ -902,6 +937,8 @@ static DEVICE_ATTR_RO(io_stat); static DEVICE_ATTR_RO(mm_stat); static DEVICE_ATTR_RO(debug_stat); + + static void zram_meta_free(struct zram *zram, u64 disksize) { size_t num_pages = disksize >> PAGE_SHIFT; @@ -932,6 +969,7 @@ 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 d1095dfdffa8..144e91061df8 100644 --- a/drivers/block/zram/zram_drv.h +++ b/drivers/block/zram/zram_drv.h @@ -61,6 +61,9 @@ struct zram_table_entry { unsigned long element; }; unsigned long value; +#ifdef CONFIG_PREEMPT_RT_BASE + spinlock_t lock; +#endif #ifdef CONFIG_ZRAM_MEMORY_TRACKING ktime_t ac_time; #endif -- 2.36.1