From 4055ae5e6d00e09ff4206843638323d1d5dfd85d Mon Sep 17 00:00:00 2001 From: Hariprasad Shenai Date: Fri, 6 Jan 2017 08:47:20 +0530 Subject: [PATCH] cxgb4: Synchronize access to mailbox The issue comes when there are multiple threads attempting to use the mailbox facility at the same time. When DCB operations and interface up/down is run in a loop for every 0.1 sec, we observed mailbox collisions. And out of the two commands one would fail with the present code, since we don't queue the second command. To overcome the above issue, added a queue to access the mailbox. Whenever a mailbox command is issued add it to the queue. If its at the head issue the mailbox command, else wait for the existing command to complete. Usually command takes less than a milli-second to complete. Also timeout from the loop, if the command under execution takes long time to run. In reality, the number of mailbox access collisions is going to be very rare since no one runs such abusive script. Signed-off-by: Hariprasad Shenai Signed-off-by: David S. Miller --- drivers/net/ethernet/chelsio/cxgb4/cxgb4.h | 8 +++ .../net/ethernet/chelsio/cxgb4/cxgb4_main.c | 3 + drivers/net/ethernet/chelsio/cxgb4/t4_hw.c | 59 ++++++++++++++++++- 3 files changed, 69 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/chelsio/cxgb4/cxgb4.h b/drivers/net/ethernet/chelsio/cxgb4/cxgb4.h index 9a49c421f86c..ad0096e74813 100644 --- a/drivers/net/ethernet/chelsio/cxgb4/cxgb4.h +++ b/drivers/net/ethernet/chelsio/cxgb4/cxgb4.h @@ -787,6 +787,10 @@ struct vf_info { bool pf_set_mac; }; +struct mbox_list { + struct list_head list; +}; + struct adapter { void __iomem *regs; void __iomem *bar2; @@ -849,6 +853,10 @@ struct adapter { struct work_struct db_drop_task; bool tid_release_task_busy; + /* lock for mailbox cmd list */ + spinlock_t mbox_lock; + struct mbox_list mlist; + /* support for mailbox command/reply logging */ #define T4_OS_LOG_MBOX_CMDS 256 struct mbox_cmd_log *mbox_log; diff --git a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c index 6f951877430b..9d2fe5140b88 100644 --- a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c +++ b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c @@ -4707,6 +4707,9 @@ static int init_one(struct pci_dev *pdev, const struct pci_device_id *ent) spin_lock_init(&adapter->stats_lock); spin_lock_init(&adapter->tid_release_lock); spin_lock_init(&adapter->win0_lock); + spin_lock_init(&adapter->mbox_lock); + + INIT_LIST_HEAD(&adapter->mlist.list); INIT_WORK(&adapter->tid_release_task, process_tid_release_list); INIT_WORK(&adapter->db_full_task, process_db_full); diff --git a/drivers/net/ethernet/chelsio/cxgb4/t4_hw.c b/drivers/net/ethernet/chelsio/cxgb4/t4_hw.c index cd5f437448d3..3c2effe6eefc 100644 --- a/drivers/net/ethernet/chelsio/cxgb4/t4_hw.c +++ b/drivers/net/ethernet/chelsio/cxgb4/t4_hw.c @@ -284,6 +284,7 @@ int t4_wr_mbox_meat_timeout(struct adapter *adap, int mbox, const void *cmd, 1, 1, 3, 5, 10, 10, 20, 50, 100, 200 }; + struct mbox_list entry; u16 access = 0; u16 execute = 0; u32 v; @@ -311,11 +312,61 @@ int t4_wr_mbox_meat_timeout(struct adapter *adap, int mbox, const void *cmd, timeout = -timeout; } + /* Queue ourselves onto the mailbox access list. When our entry is at + * the front of the list, we have rights to access the mailbox. So we + * wait [for a while] till we're at the front [or bail out with an + * EBUSY] ... + */ + spin_lock(&adap->mbox_lock); + list_add_tail(&entry.list, &adap->mlist.list); + spin_unlock(&adap->mbox_lock); + + delay_idx = 0; + ms = delay[0]; + + for (i = 0; ; i += ms) { + /* If we've waited too long, return a busy indication. This + * really ought to be based on our initial position in the + * mailbox access list but this is a start. We very rearely + * contend on access to the mailbox ... + */ + if (i > FW_CMD_MAX_TIMEOUT) { + spin_lock(&adap->mbox_lock); + list_del(&entry.list); + spin_unlock(&adap->mbox_lock); + ret = -EBUSY; + t4_record_mbox(adap, cmd, size, access, ret); + return ret; + } + + /* If we're at the head, break out and start the mailbox + * protocol. + */ + if (list_first_entry(&adap->mlist.list, struct mbox_list, + list) == &entry) + break; + + /* Delay for a bit before checking again ... */ + if (sleep_ok) { + ms = delay[delay_idx]; /* last element may repeat */ + if (delay_idx < ARRAY_SIZE(delay) - 1) + delay_idx++; + msleep(ms); + } else { + mdelay(ms); + } + } + + /* Loop trying to get ownership of the mailbox. Return an error + * if we can't gain ownership. + */ v = MBOWNER_G(t4_read_reg(adap, ctl_reg)); for (i = 0; v == MBOX_OWNER_NONE && i < 3; i++) v = MBOWNER_G(t4_read_reg(adap, ctl_reg)); - if (v != MBOX_OWNER_DRV) { + spin_lock(&adap->mbox_lock); + list_del(&entry.list); + spin_unlock(&adap->mbox_lock); ret = (v == MBOX_OWNER_FW) ? -EBUSY : -ETIMEDOUT; t4_record_mbox(adap, cmd, MBOX_LEN, access, ret); return ret; @@ -366,6 +417,9 @@ int t4_wr_mbox_meat_timeout(struct adapter *adap, int mbox, const void *cmd, execute = i + ms; t4_record_mbox(adap, cmd_rpl, MBOX_LEN, access, execute); + spin_lock(&adap->mbox_lock); + list_del(&entry.list); + spin_unlock(&adap->mbox_lock); return -FW_CMD_RETVAL_G((int)res); } } @@ -375,6 +429,9 @@ int t4_wr_mbox_meat_timeout(struct adapter *adap, int mbox, const void *cmd, dev_err(adap->pdev_dev, "command %#x in mailbox %d timed out\n", *(const u8 *)cmd, mbox); t4_report_fw_error(adap); + spin_lock(&adap->mbox_lock); + list_del(&entry.list); + spin_unlock(&adap->mbox_lock); return ret; } -- 2.20.1