From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- lib/sg_pool.c | 180 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 180 insertions(+) create mode 100644 lib/sg_pool.c (limited to 'lib/sg_pool.c') diff --git a/lib/sg_pool.c b/lib/sg_pool.c new file mode 100644 index 000000000..9bfe60ca3 --- /dev/null +++ b/lib/sg_pool.c @@ -0,0 +1,180 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include +#include +#include +#include + +#define SG_MEMPOOL_NR ARRAY_SIZE(sg_pools) +#define SG_MEMPOOL_SIZE 2 + +struct sg_pool { + size_t size; + char *name; + struct kmem_cache *slab; + mempool_t *pool; +}; + +#define SP(x) { .size = x, "sgpool-" __stringify(x) } +#if (SG_CHUNK_SIZE < 32) +#error SG_CHUNK_SIZE is too small (must be 32 or greater) +#endif +static struct sg_pool sg_pools[] = { + SP(8), + SP(16), +#if (SG_CHUNK_SIZE > 32) + SP(32), +#if (SG_CHUNK_SIZE > 64) + SP(64), +#if (SG_CHUNK_SIZE > 128) + SP(128), +#if (SG_CHUNK_SIZE > 256) +#error SG_CHUNK_SIZE is too large (256 MAX) +#endif +#endif +#endif +#endif + SP(SG_CHUNK_SIZE) +}; +#undef SP + +static inline unsigned int sg_pool_index(unsigned short nents) +{ + unsigned int index; + + BUG_ON(nents > SG_CHUNK_SIZE); + + if (nents <= 8) + index = 0; + else + index = get_count_order(nents) - 3; + + return index; +} + +static void sg_pool_free(struct scatterlist *sgl, unsigned int nents) +{ + struct sg_pool *sgp; + + sgp = sg_pools + sg_pool_index(nents); + mempool_free(sgl, sgp->pool); +} + +static struct scatterlist *sg_pool_alloc(unsigned int nents, gfp_t gfp_mask) +{ + struct sg_pool *sgp; + + sgp = sg_pools + sg_pool_index(nents); + return mempool_alloc(sgp->pool, gfp_mask); +} + +/** + * sg_free_table_chained - Free a previously mapped sg table + * @table: The sg table header to use + * @nents_first_chunk: size of the first_chunk SGL passed to + * sg_alloc_table_chained + * + * Description: + * Free an sg table previously allocated and setup with + * sg_alloc_table_chained(). + * + * @nents_first_chunk has to be same with that same parameter passed + * to sg_alloc_table_chained(). + * + **/ +void sg_free_table_chained(struct sg_table *table, + unsigned nents_first_chunk) +{ + if (table->orig_nents <= nents_first_chunk) + return; + + if (nents_first_chunk == 1) + nents_first_chunk = 0; + + __sg_free_table(table, SG_CHUNK_SIZE, nents_first_chunk, sg_pool_free, + table->orig_nents); +} +EXPORT_SYMBOL_GPL(sg_free_table_chained); + +/** + * sg_alloc_table_chained - Allocate and chain SGLs in an sg table + * @table: The sg table header to use + * @nents: Number of entries in sg list + * @first_chunk: first SGL + * @nents_first_chunk: number of the SGL of @first_chunk + * + * Description: + * Allocate and chain SGLs in an sg table. If @nents@ is larger than + * @nents_first_chunk a chained sg table will be setup. @first_chunk is + * ignored if nents_first_chunk <= 1 because user expects the SGL points + * non-chain SGL. + * + **/ +int sg_alloc_table_chained(struct sg_table *table, int nents, + struct scatterlist *first_chunk, unsigned nents_first_chunk) +{ + int ret; + + BUG_ON(!nents); + + if (first_chunk && nents_first_chunk) { + if (nents <= nents_first_chunk) { + table->nents = table->orig_nents = nents; + sg_init_table(table->sgl, nents); + return 0; + } + } + + /* User supposes that the 1st SGL includes real entry */ + if (nents_first_chunk <= 1) { + first_chunk = NULL; + nents_first_chunk = 0; + } + + ret = __sg_alloc_table(table, nents, SG_CHUNK_SIZE, + first_chunk, nents_first_chunk, + GFP_ATOMIC, sg_pool_alloc); + if (unlikely(ret)) + sg_free_table_chained(table, nents_first_chunk); + return ret; +} +EXPORT_SYMBOL_GPL(sg_alloc_table_chained); + +static __init int sg_pool_init(void) +{ + int i; + + for (i = 0; i < SG_MEMPOOL_NR; i++) { + struct sg_pool *sgp = sg_pools + i; + int size = sgp->size * sizeof(struct scatterlist); + + sgp->slab = kmem_cache_create(sgp->name, size, 0, + SLAB_HWCACHE_ALIGN, NULL); + if (!sgp->slab) { + printk(KERN_ERR "SG_POOL: can't init sg slab %s\n", + sgp->name); + goto cleanup_sdb; + } + + sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE, + sgp->slab); + if (!sgp->pool) { + printk(KERN_ERR "SG_POOL: can't init sg mempool %s\n", + sgp->name); + goto cleanup_sdb; + } + } + + return 0; + +cleanup_sdb: + for (i = 0; i < SG_MEMPOOL_NR; i++) { + struct sg_pool *sgp = sg_pools + i; + + mempool_destroy(sgp->pool); + kmem_cache_destroy(sgp->slab); + } + + return -ENOMEM; +} + +subsys_initcall(sg_pool_init); -- cgit v1.3.1