diff options
Diffstat (limited to 'drivers/scsi/scsi.c')
| -rw-r--r-- | drivers/scsi/scsi.c | 149 |
1 files changed, 112 insertions, 37 deletions
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c index 2cf9a625f22..f6980bd9d8f 100644 --- a/drivers/scsi/scsi.c +++ b/drivers/scsi/scsi.c @@ -330,30 +330,16 @@ void scsi_put_command(struct scsi_cmnd *cmd) } EXPORT_SYMBOL(scsi_put_command); -/** - * scsi_setup_command_freelist - Setup the command freelist for a scsi host. - * @shost: host to allocate the freelist for. - * - * Description: The command freelist protects against system-wide out of memory - * deadlock by preallocating one SCSI command structure for each host, so the - * system can always write to a swap file on a device associated with that host. - * - * Returns: Nothing. - */ -int scsi_setup_command_freelist(struct Scsi_Host *shost) +static struct scsi_host_cmd_pool *scsi_get_host_cmd_pool(gfp_t gfp_mask) { - struct scsi_host_cmd_pool *pool; - struct scsi_cmnd *cmd; - - spin_lock_init(&shost->free_list_lock); - INIT_LIST_HEAD(&shost->free_list); - + struct scsi_host_cmd_pool *retval = NULL, *pool; /* * Select a command slab for this host and create it if not * yet existent. */ mutex_lock(&host_cmd_pool_mutex); - pool = (shost->unchecked_isa_dma ? &scsi_cmd_dma_pool : &scsi_cmd_pool); + pool = (gfp_mask & __GFP_DMA) ? &scsi_cmd_dma_pool : + &scsi_cmd_pool; if (!pool->users) { pool->cmd_slab = kmem_cache_create(pool->cmd_name, sizeof(struct scsi_cmnd), 0, @@ -371,28 +357,122 @@ int scsi_setup_command_freelist(struct Scsi_Host *shost) } pool->users++; - shost->cmd_pool = pool; + retval = pool; + fail: mutex_unlock(&host_cmd_pool_mutex); + return retval; +} + +static void scsi_put_host_cmd_pool(gfp_t gfp_mask) +{ + struct scsi_host_cmd_pool *pool; + mutex_lock(&host_cmd_pool_mutex); + pool = (gfp_mask & __GFP_DMA) ? &scsi_cmd_dma_pool : + &scsi_cmd_pool; /* - * Get one backup command for this host. + * This may happen if a driver has a mismatched get and put + * of the command pool; the driver should be implicated in + * the stack trace */ - cmd = scsi_pool_alloc_command(shost->cmd_pool, GFP_KERNEL); - if (!cmd) - goto fail2; + BUG_ON(pool->users == 0); - list_add(&cmd->list, &shost->free_list); - return 0; - - fail2: - mutex_lock(&host_cmd_pool_mutex); if (!--pool->users) { kmem_cache_destroy(pool->cmd_slab); kmem_cache_destroy(pool->sense_slab); } - fail: mutex_unlock(&host_cmd_pool_mutex); - return -ENOMEM; +} + +/** + * scsi_allocate_command - get a fully allocated SCSI command + * @gfp_mask: allocation mask + * + * This function is for use outside of the normal host based pools. + * It allocates the relevant command and takes an additional reference + * on the pool it used. This function *must* be paired with + * scsi_free_command which also has the identical mask, otherwise the + * free pool counts will eventually go wrong and you'll trigger a bug. + * + * This function should *only* be used by drivers that need a static + * command allocation at start of day for internal functions. + */ +struct scsi_cmnd *scsi_allocate_command(gfp_t gfp_mask) +{ + struct scsi_host_cmd_pool *pool = scsi_get_host_cmd_pool(gfp_mask); + + if (!pool) + return NULL; + + return scsi_pool_alloc_command(pool, gfp_mask); +} +EXPORT_SYMBOL(scsi_allocate_command); + +/** + * scsi_free_command - free a command allocated by scsi_allocate_command + * @gfp_mask: mask used in the original allocation + * @cmd: command to free + * + * Note: using the original allocation mask is vital because that's + * what determines which command pool we use to free the command. Any + * mismatch will cause the system to BUG eventually. + */ +void scsi_free_command(gfp_t gfp_mask, struct scsi_cmnd *cmd) +{ + struct scsi_host_cmd_pool *pool = scsi_get_host_cmd_pool(gfp_mask); + + /* + * this could trigger if the mask to scsi_allocate_command + * doesn't match this mask. Otherwise we're guaranteed that this + * succeeds because scsi_allocate_command must have taken a reference + * on the pool + */ + BUG_ON(!pool); + + scsi_pool_free_command(pool, cmd); + /* + * scsi_put_host_cmd_pool is called twice; once to release the + * reference we took above, and once to release the reference + * originally taken by scsi_allocate_command + */ + scsi_put_host_cmd_pool(gfp_mask); + scsi_put_host_cmd_pool(gfp_mask); +} +EXPORT_SYMBOL(scsi_free_command); + +/** + * scsi_setup_command_freelist - Setup the command freelist for a scsi host. + * @shost: host to allocate the freelist for. + * + * Description: The command freelist protects against system-wide out of memory + * deadlock by preallocating one SCSI command structure for each host, so the + * system can always write to a swap file on a device associated with that host. + * + * Returns: Nothing. + */ +int scsi_setup_command_freelist(struct Scsi_Host *shost) +{ + struct scsi_cmnd *cmd; + const gfp_t gfp_mask = shost->unchecked_isa_dma ? GFP_DMA : GFP_KERNEL; + + spin_lock_init(&shost->free_list_lock); + INIT_LIST_HEAD(&shost->free_list); + + shost->cmd_pool = scsi_get_host_cmd_pool(gfp_mask); + + if (!shost->cmd_pool) + return -ENOMEM; + + /* + * Get one backup command for this host. + */ + cmd = scsi_pool_alloc_command(shost->cmd_pool, gfp_mask); + if (!cmd) { + scsi_put_host_cmd_pool(gfp_mask); + return -ENOMEM; + } + list_add(&cmd->list, &shost->free_list); + return 0; } /** @@ -408,13 +488,8 @@ void scsi_destroy_command_freelist(struct Scsi_Host *shost) list_del_init(&cmd->list); scsi_pool_free_command(shost->cmd_pool, cmd); } - - mutex_lock(&host_cmd_pool_mutex); - if (!--shost->cmd_pool->users) { - kmem_cache_destroy(shost->cmd_pool->cmd_slab); - kmem_cache_destroy(shost->cmd_pool->sense_slab); - } - mutex_unlock(&host_cmd_pool_mutex); + shost->cmd_pool = NULL; + scsi_put_host_cmd_pool(shost->unchecked_isa_dma ? GFP_DMA : GFP_KERNEL); } #ifdef CONFIG_SCSI_LOGGING |