From 3f418f28c07c66351c686f78cb455cfda3ffcb69 Mon Sep 17 00:00:00 2001 From: Mike Galbraith Date: Thu, 31 Mar 2016 04:08:28 +0200 Subject: [PATCH 310/365] drivers/block/zram: Replace bit spinlocks with rtmutex for -rt 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 | 30 +++++++++++++------------ drivers/block/zram/zram_drv.h | 41 +++++++++++++++++++++++++++++++++++ 2 files changed, 57 insertions(+), 14 deletions(-) diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index d64a53d3270a..c864ad57348a 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -528,6 +528,8 @@ static struct zram_meta *zram_meta_alloc(char *pool_name, u64 disksize) goto out_error; } + zram_meta_init_table_locks(meta, disksize); + return meta; out_error: @@ -576,12 +578,12 @@ static int zram_decompress_page(struct zram *zram, char *mem, u32 index) unsigned long handle; unsigned int size; - bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); + zram_lock_table(&meta->table[index]); handle = meta->table[index].handle; size = zram_get_obj_size(meta, index); if (!handle || zram_test_flag(meta, index, ZRAM_ZERO)) { - bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); + zram_unlock_table(&meta->table[index]); memset(mem, 0, PAGE_SIZE); return 0; } @@ -596,7 +598,7 @@ static int zram_decompress_page(struct zram *zram, char *mem, u32 index) zcomp_stream_put(zram->comp); } zs_unmap_object(meta->mem_pool, handle); - bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); + zram_unlock_table(&meta->table[index]); /* Should NEVER happen. Return bio error if it does. */ if (unlikely(ret)) { @@ -616,14 +618,14 @@ static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec, struct zram_meta *meta = zram->meta; page = bvec->bv_page; - bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); + zram_lock_table(&meta->table[index]); if (unlikely(!meta->table[index].handle) || zram_test_flag(meta, index, ZRAM_ZERO)) { - bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); + zram_unlock_table(&meta->table[index]); handle_zero_page(bvec); return 0; } - bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); + zram_unlock_table(&meta->table[index]); if (is_partial_io(bvec)) /* Use a temporary buffer to decompress the page */ @@ -700,10 +702,10 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, if (user_mem) kunmap_atomic(user_mem); /* Free memory associated with this sector now. */ - bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); + zram_lock_table(&meta->table[index]); zram_free_page(zram, index); zram_set_flag(meta, index, ZRAM_ZERO); - bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); + zram_unlock_table(&meta->table[index]); atomic64_inc(&zram->stats.zero_pages); ret = 0; @@ -794,12 +796,12 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, * Free memory associated with this sector * before overwriting unused sectors. */ - bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); + zram_lock_table(&meta->table[index]); zram_free_page(zram, index); meta->table[index].handle = handle; zram_set_obj_size(meta, index, clen); - bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); + zram_unlock_table(&meta->table[index]); /* Update stats */ atomic64_add(clen, &zram->stats.compr_data_size); @@ -842,9 +844,9 @@ static void zram_bio_discard(struct zram *zram, u32 index, } while (n >= PAGE_SIZE) { - bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); + zram_lock_table(&meta->table[index]); zram_free_page(zram, index); - bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); + zram_unlock_table(&meta->table[index]); atomic64_inc(&zram->stats.notify_free); index++; n -= PAGE_SIZE; @@ -973,9 +975,9 @@ static void zram_slot_free_notify(struct block_device *bdev, zram = bdev->bd_disk->private_data; meta = zram->meta; - bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); + zram_lock_table(&meta->table[index]); zram_free_page(zram, index); - bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); + zram_unlock_table(&meta->table[index]); atomic64_inc(&zram->stats.notify_free); } diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h index 6d2475a39e84..87278e8aa61e 100644 --- a/drivers/block/zram/zram_drv.h +++ b/drivers/block/zram/zram_drv.h @@ -72,6 +72,9 @@ enum zram_pageflags { struct zram_table_entry { unsigned long handle; unsigned long value; +#ifdef CONFIG_PREEMPT_RT_BASE + spinlock_t lock; +#endif }; struct zram_stats { @@ -119,4 +122,42 @@ struct zram { */ bool claim; /* Protected by bdev->bd_mutex */ }; + +#ifndef CONFIG_PREEMPT_RT_BASE +static inline void zram_lock_table(struct zram_table_entry *table) +{ + bit_spin_lock(ZRAM_ACCESS, &table->value); +} + +static inline void zram_unlock_table(struct zram_table_entry *table) +{ + bit_spin_unlock(ZRAM_ACCESS, &table->value); +} + +static inline void zram_meta_init_table_locks(struct zram_meta *meta, u64 disksize) { } +#else /* CONFIG_PREEMPT_RT_BASE */ +static inline void zram_lock_table(struct zram_table_entry *table) +{ + spin_lock(&table->lock); + __set_bit(ZRAM_ACCESS, &table->value); +} + +static inline void zram_unlock_table(struct zram_table_entry *table) +{ + __clear_bit(ZRAM_ACCESS, &table->value); + spin_unlock(&table->lock); +} + +static inline void zram_meta_init_table_locks(struct zram_meta *meta, u64 disksize) +{ + size_t num_pages = disksize >> PAGE_SHIFT; + size_t index; + + for (index = 0; index < num_pages; index++) { + spinlock_t *lock = &meta->table[index].lock; + spin_lock_init(lock); + } +} +#endif /* CONFIG_PREEMPT_RT_BASE */ + #endif -- 2.28.0