From: "Michael Chan" Subject: [PATCH 5/5] cnic: Fix locking in init/exit calls. Date: Fri, 14 Aug 2009 18:49:47 -0700 Message-ID: <1250300987-18407-6-git-send-email-mchan@broadcom.com> References: <1250300987-18407-1-git-send-email-mchan@broadcom.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, linux-scsi@vger.kernel.org To: davem@davemloft.net, James.Bottomley@HansenPartnership.com, michaelc@cs.wisc.edu Return-path: Received: from mms2.broadcom.com ([216.31.210.18]:1454 "EHLO mms2.broadcom.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755494AbZHOBnA (ORCPT ); Fri, 14 Aug 2009 21:43:00 -0400 In-Reply-To: <1250300987-18407-1-git-send-email-mchan@broadcom.com> Sender: netdev-owner@vger.kernel.org List-ID: The slow path ulp_init and ulp_exit calls to the bnx2i driver are sleepable calls and therefore should not be protected using rcu_read_lock. Fix it by using mutex and refcount during these calls. cnic_unregister_driver() will now wait for the refcount to go to zero before completing the call. Signed-off-by: Michael Chan Reviewed-by: Benjamin Li --- drivers/net/cnic.c | 48 +++++++++++++++++++++++++++++++++++++++--------- drivers/net/cnic_if.h | 1 + 2 files changed, 40 insertions(+), 9 deletions(-) diff --git a/drivers/net/cnic.c b/drivers/net/cnic.c index 4ff618a..74c3429 100644 --- a/drivers/net/cnic.c +++ b/drivers/net/cnic.c @@ -138,6 +138,16 @@ static struct cnic_dev *cnic_from_netdev(struct net_device *netdev) return NULL; } +static inline void ulp_get(struct cnic_ulp_ops *ulp_ops) +{ + atomic_inc(&ulp_ops->ref_count); +} + +static inline void ulp_put(struct cnic_ulp_ops *ulp_ops) +{ + atomic_dec(&ulp_ops->ref_count); +} + static void cnic_ctx_wr(struct cnic_dev *dev, u32 cid_addr, u32 off, u32 val) { struct cnic_local *cp = dev->cnic_priv; @@ -358,6 +368,7 @@ int cnic_register_driver(int ulp_type, struct cnic_ulp_ops *ulp_ops) } read_unlock(&cnic_dev_lock); + atomic_set(&ulp_ops->ref_count, 0); rcu_assign_pointer(cnic_ulp_tbl[ulp_type], ulp_ops); mutex_unlock(&cnic_lock); @@ -379,6 +390,8 @@ int cnic_register_driver(int ulp_type, struct cnic_ulp_ops *ulp_ops) int cnic_unregister_driver(int ulp_type) { struct cnic_dev *dev; + struct cnic_ulp_ops *ulp_ops; + int i = 0; if (ulp_type >= MAX_CNIC_ULP_TYPE) { printk(KERN_ERR PFX "cnic_unregister_driver: Bad type %d\n", @@ -386,7 +399,8 @@ int cnic_unregister_driver(int ulp_type) return -EINVAL; } mutex_lock(&cnic_lock); - if (!cnic_ulp_tbl[ulp_type]) { + ulp_ops = cnic_ulp_tbl[ulp_type]; + if (!ulp_ops) { printk(KERN_ERR PFX "cnic_unregister_driver: Type %d has not " "been registered\n", ulp_type); goto out_unlock; @@ -411,6 +425,14 @@ int cnic_unregister_driver(int ulp_type) mutex_unlock(&cnic_lock); synchronize_rcu(); + while ((atomic_read(&ulp_ops->ref_count) != 0) && (i < 20)) { + msleep(100); + i++; + } + + if (atomic_read(&ulp_ops->ref_count) != 0) + printk(KERN_WARNING PFX "%s: Failed waiting for ref count to go" + " to zero.\n", dev->netdev->name); return 0; out_unlock: @@ -1161,19 +1183,23 @@ static void cnic_ulp_init(struct cnic_dev *dev) int i; struct cnic_local *cp = dev->cnic_priv; - rcu_read_lock(); for (i = 0; i < MAX_CNIC_ULP_TYPE_EXT; i++) { struct cnic_ulp_ops *ulp_ops; - ulp_ops = rcu_dereference(cnic_ulp_tbl[i]); - if (!ulp_ops || !ulp_ops->cnic_init) + mutex_lock(&cnic_lock); + ulp_ops = cnic_ulp_tbl[i]; + if (!ulp_ops || !ulp_ops->cnic_init) { + mutex_unlock(&cnic_lock); continue; + } + ulp_get(ulp_ops); + mutex_unlock(&cnic_lock); if (!test_and_set_bit(ULP_F_INIT, &cp->ulp_flags[i])) ulp_ops->cnic_init(dev); + ulp_put(ulp_ops); } - rcu_read_unlock(); } static void cnic_ulp_exit(struct cnic_dev *dev) @@ -1181,19 +1207,23 @@ static void cnic_ulp_exit(struct cnic_dev *dev) int i; struct cnic_local *cp = dev->cnic_priv; - rcu_read_lock(); for (i = 0; i < MAX_CNIC_ULP_TYPE_EXT; i++) { struct cnic_ulp_ops *ulp_ops; - ulp_ops = rcu_dereference(cnic_ulp_tbl[i]); - if (!ulp_ops || !ulp_ops->cnic_exit) + mutex_lock(&cnic_lock); + ulp_ops = cnic_ulp_tbl[i]; + if (!ulp_ops || !ulp_ops->cnic_exit) { + mutex_unlock(&cnic_lock); continue; + } + ulp_get(ulp_ops); + mutex_unlock(&cnic_lock); if (test_and_clear_bit(ULP_F_INIT, &cp->ulp_flags[i])) ulp_ops->cnic_exit(dev); + ulp_put(ulp_ops); } - rcu_read_unlock(); } static int cnic_cm_offload_pg(struct cnic_sock *csk) diff --git a/drivers/net/cnic_if.h b/drivers/net/cnic_if.h index d1bce27..a492357 100644 --- a/drivers/net/cnic_if.h +++ b/drivers/net/cnic_if.h @@ -290,6 +290,7 @@ struct cnic_ulp_ops { void (*iscsi_nl_send_msg)(struct cnic_dev *dev, u32 msg_type, char *data, u16 data_size); struct module *owner; + atomic_t ref_count; }; extern int cnic_register_driver(int ulp_type, struct cnic_ulp_ops *ulp_ops); -- 1.5.6.GIT