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Miller" Cc: linux-s390@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH net v2 1/3] s390/ism: Fix locking for forwarding of IRQs and events to clients Date: Fri, 7 Jul 2023 12:56:20 +0200 Message-Id: <20230707105622.3332261-2-schnelle@linux.ibm.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230707105622.3332261-1-schnelle@linux.ibm.com> References: <20230707105622.3332261-1-schnelle@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: zRO7XdwlnkxnintcFzE1pv6pUOdan_Ie X-Proofpoint-GUID: A-WEsBEOUu7_IeT7D3sk8696nU1M5dAs X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.957,Hydra:6.0.591,FMLib:17.11.176.26 definitions=2023-07-07_06,2023-07-06_02,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 priorityscore=1501 malwarescore=0 clxscore=1015 phishscore=0 adultscore=0 spamscore=0 impostorscore=0 mlxlogscore=869 mlxscore=0 bulkscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2305260000 definitions=main-2307070097 X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_EF,RCVD_IN_MSPIKE_H5,RCVD_IN_MSPIKE_WL, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The clients array references all registered clients and is protected by the clients_lock. Besides its use as general list of clients the clients array is accessed in ism_handle_irq() to forward ISM device events to clients. While the clients_lock is taken in the IRQ handler when calling handle_event() it is however incorrectly not held during the client->handle_irq() call and for the preceding clients[] access leaving it unprotected against concurrent client (un-)registration. Furthermore the accesses to ism->sba_client_arr[] in ism_register_dmb() and ism_unregister_dmb() are not protected by any lock. This is especially problematic as the client ID from the ism->sba_client_arr[] is not checked against NO_CLIENT and neither is the client pointer checked. Instead of expanding the use of the clients_lock further add a separate array in struct ism_dev which references clients subscribed to the device's events and IRQs. This array is protected by ism->lock which is already taken in ism_handle_irq() and can be taken outside the IRQ handler when adding/removing subscribers or the accessing ism->sba_client_arr[]. This also means that the clients_lock is no longer taken in IRQ context. Fixes: 89e7d2ba61b7 ("net/ism: Add new API for client registration") Signed-off-by: Niklas Schnelle --- drivers/s390/net/ism_drv.c | 44 +++++++++++++++++++++++++++++++------- include/linux/ism.h | 1 + 2 files changed, 37 insertions(+), 8 deletions(-) diff --git a/drivers/s390/net/ism_drv.c b/drivers/s390/net/ism_drv.c index 9b5fccdbc7d6..b664e4a08645 100644 --- a/drivers/s390/net/ism_drv.c +++ b/drivers/s390/net/ism_drv.c @@ -47,6 +47,15 @@ static struct ism_dev_list ism_dev_list = { .mutex = __MUTEX_INITIALIZER(ism_dev_list.mutex), }; +static void ism_setup_forwarding(struct ism_client *client, struct ism_dev *ism) +{ + unsigned long flags; + + spin_lock_irqsave(&ism->lock, flags); + ism->subs[client->id] = client; + spin_unlock_irqrestore(&ism->lock, flags); +} + int ism_register_client(struct ism_client *client) { struct ism_dev *ism; @@ -71,6 +80,7 @@ int ism_register_client(struct ism_client *client) list_for_each_entry(ism, &ism_dev_list.list, list) { ism->priv[i] = NULL; client->add(ism); + ism_setup_forwarding(client, ism); } } mutex_unlock(&ism_dev_list.mutex); @@ -92,6 +102,9 @@ int ism_unregister_client(struct ism_client *client) max_client--; spin_unlock_irqrestore(&clients_lock, flags); list_for_each_entry(ism, &ism_dev_list.list, list) { + spin_lock_irqsave(&ism->lock, flags); + /* Stop forwarding IRQs and events */ + ism->subs[client->id] = NULL; for (int i = 0; i < ISM_NR_DMBS; ++i) { if (ism->sba_client_arr[i] == client->id) { pr_err("%s: attempt to unregister client '%s'" @@ -101,6 +114,7 @@ int ism_unregister_client(struct ism_client *client) goto out; } } + spin_unlock_irqrestore(&ism->lock, flags); } out: mutex_unlock(&ism_dev_list.mutex); @@ -328,6 +342,7 @@ int ism_register_dmb(struct ism_dev *ism, struct ism_dmb *dmb, struct ism_client *client) { union ism_reg_dmb cmd; + unsigned long flags; int ret; ret = ism_alloc_dmb(ism, dmb); @@ -351,7 +366,9 @@ int ism_register_dmb(struct ism_dev *ism, struct ism_dmb *dmb, goto out; } dmb->dmb_tok = cmd.response.dmb_tok; + spin_lock_irqsave(&ism->lock, flags); ism->sba_client_arr[dmb->sba_idx - ISM_DMB_BIT_OFFSET] = client->id; + spin_unlock_irqrestore(&ism->lock, flags); out: return ret; } @@ -360,6 +377,7 @@ EXPORT_SYMBOL_GPL(ism_register_dmb); int ism_unregister_dmb(struct ism_dev *ism, struct ism_dmb *dmb) { union ism_unreg_dmb cmd; + unsigned long flags; int ret; memset(&cmd, 0, sizeof(cmd)); @@ -368,7 +386,9 @@ int ism_unregister_dmb(struct ism_dev *ism, struct ism_dmb *dmb) cmd.request.dmb_tok = dmb->dmb_tok; + spin_lock_irqsave(&ism->lock, flags); ism->sba_client_arr[dmb->sba_idx - ISM_DMB_BIT_OFFSET] = NO_CLIENT; + spin_unlock_irqrestore(&ism->lock, flags); ret = ism_cmd(ism, &cmd); if (ret && ret != ISM_ERROR) @@ -491,6 +511,7 @@ static u16 ism_get_chid(struct ism_dev *ism) static void ism_handle_event(struct ism_dev *ism) { struct ism_event *entry; + struct ism_client *clt; int i; while ((ism->ieq_idx + 1) != READ_ONCE(ism->ieq->header.idx)) { @@ -499,21 +520,21 @@ static void ism_handle_event(struct ism_dev *ism) entry = &ism->ieq->entry[ism->ieq_idx]; debug_event(ism_debug_info, 2, entry, sizeof(*entry)); - spin_lock(&clients_lock); - for (i = 0; i < max_client; ++i) - if (clients[i]) - clients[i]->handle_event(ism, entry); - spin_unlock(&clients_lock); + for (i = 0; i < max_client; ++i) { + clt = ism->subs[i]; + if (clt) + clt->handle_event(ism, entry); + } } } static irqreturn_t ism_handle_irq(int irq, void *data) { struct ism_dev *ism = data; - struct ism_client *clt; unsigned long bit, end; unsigned long *bv; u16 dmbemask; + u8 client_id; bv = (void *) &ism->sba->dmb_bits[ISM_DMB_WORD_OFFSET]; end = sizeof(ism->sba->dmb_bits) * BITS_PER_BYTE - ISM_DMB_BIT_OFFSET; @@ -530,8 +551,10 @@ static irqreturn_t ism_handle_irq(int irq, void *data) dmbemask = ism->sba->dmbe_mask[bit + ISM_DMB_BIT_OFFSET]; ism->sba->dmbe_mask[bit + ISM_DMB_BIT_OFFSET] = 0; barrier(); - clt = clients[ism->sba_client_arr[bit]]; - clt->handle_irq(ism, bit + ISM_DMB_BIT_OFFSET, dmbemask); + client_id = ism->sba_client_arr[bit]; + if (unlikely(client_id == NO_CLIENT || !ism->subs[client_id])) + continue; + ism->subs[client_id]->handle_irq(ism, bit + ISM_DMB_BIT_OFFSET, dmbemask); } if (ism->sba->e) { @@ -554,6 +577,7 @@ static void ism_dev_add_work_func(struct work_struct *work) add_work); client->add(client->tgt_ism); + ism_setup_forwarding(client, client->tgt_ism); atomic_dec(&client->tgt_ism->add_dev_cnt); wake_up(&client->tgt_ism->waitq); } @@ -691,7 +715,11 @@ static void ism_dev_remove_work_func(struct work_struct *work) { struct ism_client *client = container_of(work, struct ism_client, remove_work); + unsigned long flags; + spin_lock_irqsave(&client->tgt_ism->lock, flags); + client->tgt_ism->subs[client->id] = NULL; + spin_unlock_irqrestore(&client->tgt_ism->lock, flags); client->remove(client->tgt_ism); atomic_dec(&client->tgt_ism->free_clients_cnt); wake_up(&client->tgt_ism->waitq); diff --git a/include/linux/ism.h b/include/linux/ism.h index ea2bcdae7401..5160d47e5ea9 100644 --- a/include/linux/ism.h +++ b/include/linux/ism.h @@ -44,6 +44,7 @@ struct ism_dev { u64 local_gid; int ieq_idx; + struct ism_client *subs[MAX_CLIENTS]; atomic_t free_clients_cnt; atomic_t add_dev_cnt; wait_queue_head_t waitq; -- 2.39.2