Avoid that the following warning is reported when a SCSI LLD kernel module is unloaded:
WARNING: CPU: 5 PID: 228 at kernel/module.c:954 module_put+0x207/0x220() Call Trace: [<ffffffff814d1fcf>] dump_stack+0x4c/0x65 [<ffffffff81053ada>] warn_slowpath_common+0x8a/0xc0 [<ffffffff81053bca>] warn_slowpath_null+0x1a/0x20 [<ffffffff810d0507>] module_put+0x207/0x220 [<ffffffffa000bea8>] scsi_device_put+0x48/0x50 [scsi_mod] [<ffffffffa03676d2>] scsi_disk_put+0x32/0x50 [sd_mod] [<ffffffffa0368d4c>] sd_shutdown+0x8c/0x150 [sd_mod] [<ffffffffa0368e79>] sd_remove+0x69/0xc0 [sd_mod] [<ffffffff813457ef>] __device_release_driver+0x7f/0xf0 [<ffffffff81345885>] device_release_driver+0x25/0x40 [<ffffffff81345134>] bus_remove_device+0x124/0x1b0 [<ffffffff8134189e>] device_del+0x13e/0x250 [<ffffffffa001cdcd>] __scsi_remove_device+0xcd/0xe0 [scsi_mod] [<ffffffffa001b39f>] scsi_forget_host+0x6f/0x80 [scsi_mod] [<ffffffffa000d5f6>] scsi_remove_host+0x86/0x140 [scsi_mod] [<ffffffffa07d5c0b>] srp_remove_work+0x9b/0x210 [ib_srp] [<ffffffff8106fd28>] process_one_work+0x1d8/0x780 [<ffffffff810703eb>] worker_thread+0x11b/0x4a0 [<ffffffff81075a6f>] kthread+0xef/0x110 [<ffffffff814dad6c>] ret_from_fork+0x7c/0xb0 See also patch "module: Remove stop_machine from module unloading" (Masami Hiramatsu; commit e513cc1c07e2; kernel v3.19-rc1). Signed-off-by: Bart Van Assche <[email protected]> Cc: Christoph Hellwig <[email protected]> Cc: Hannes Reinecke <[email protected]> --- drivers/scsi/hosts.c | 1 + drivers/scsi/scsi.c | 13 ++++--------- include/scsi/scsi_host.h | 3 +++ 3 files changed, 8 insertions(+), 9 deletions(-) diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c index 8bb173e..e9155d0 100644 --- a/drivers/scsi/hosts.c +++ b/drivers/scsi/hosts.c @@ -380,6 +380,7 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize) shost->host_lock = &shost->default_lock; spin_lock_init(shost->host_lock); + atomic_set(&shost->module_refcnt, 0); shost->shost_state = SHOST_CREATED; INIT_LIST_HEAD(&shost->__devices); INIT_LIST_HEAD(&shost->__targets); diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c index e028854..ed325d1 100644 --- a/drivers/scsi/scsi.c +++ b/drivers/scsi/scsi.c @@ -988,7 +988,8 @@ int scsi_device_get(struct scsi_device *sdev) return -ENXIO; /* We can fail this if we're doing SCSI operations * from module exit (like cache flush) */ - try_module_get(sdev->host->hostt->module); + if (try_module_get(sdev->host->hostt->module)) + atomic_inc(&sdev->host->module_refcnt); return 0; } @@ -1004,14 +1005,8 @@ EXPORT_SYMBOL(scsi_device_get); */ void scsi_device_put(struct scsi_device *sdev) { -#ifdef CONFIG_MODULE_UNLOAD - struct module *module = sdev->host->hostt->module; - - /* The module refcount will be zero if scsi_device_get() - * was called from a module removal routine */ - if (module && module_refcount(module) != 0) - module_put(module); -#endif + if (atomic_dec_if_positive(&sdev->host->module_refcnt) >= 0) + module_put(sdev->host->hostt->module); put_device(&sdev->sdev_gendev); } EXPORT_SYMBOL(scsi_device_put); diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h index 019e668..b8e6f01 100644 --- a/include/scsi/scsi_host.h +++ b/include/scsi/scsi_host.h @@ -566,6 +566,9 @@ struct Scsi_Host { struct scsi_host_template *hostt; struct scsi_transport_template *transportt; + /* Number of LLD kernel module references held by the SCSI core. */ + atomic_t module_refcnt; + /* * Area to keep a shared tag map (if needed, will be * NULL if not). -- 2.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
