From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: module: fix module_refcount() return when running in a module exit routine Date: Sun, 18 Jan 2015 08:55:46 -0800 Message-ID: <1421600146.2080.8.camel@HansenPartnership.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: Sender: linux-kernel-owner@vger.kernel.org To: "rusty@rustcorp.com.au" , "masami.hiramatsu.pt@hitachi.com" Cc: linux-kernel , linux-scsi List-Id: linux-scsi@vger.kernel.org From: James Bottomley After e513cc1 module: Remove stop_machine from module unloading, module_refcount() is returning (unsigned long)-1 when called from within a routine that runs in module_exit. This is confusing the scsi device put code which is coded to detect a module_refcount() of zero for running within a module exit routine and not try to do another module_put. The fix is to restore the original behaviour of module_refcount() and return zero if we're running inside an exit routine. Fixes: e513cc1c07e2ab93a4514eec9833e031df3e30bb Reported-by: Bart Van Assche Signed-off-by: James Bottomley --- diff --git a/kernel/module.c b/kernel/module.c index 3965511..c33a113 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -774,7 +774,12 @@ static int try_stop_module(struct module *mod, int flags, int *forced) unsigned long module_refcount(struct module *mod) { - return (unsigned long)atomic_read(&mod->refcnt) - MODULE_REF_BASE; + unsigned long ret = atomic_read(&mod->refcnt); + + if (ret == 0) + /* ref is already zero (probably in module exit) */ + return 0; + return ret - MODULE_REF_BASE; } EXPORT_SYMBOL(module_refcount);