From a00918d0521df1c7a2ec9143142a3ea998c8526d Mon Sep 17 00:00:00 2001 From: Chris Bainbridge Date: Tue, 19 May 2015 16:30:51 +0300 Subject: [PATCH] usb: host: xhci: add mutex for non-thread-safe data Regression in commit 638139eb95d2 ("usb: hub: allow to process more usb hub events in parallel") The regression resulted in intermittent failure to initialise a 10-port hub (with three internal VL812 4-port hub controllers) on boot, with a failure rate of around 8%, due to multiple race conditions when accessing addr_dev and slot_id in struct xhci_hcd. This regression also exposed a problem with xhci_setup_device, which "should be protected by the usb_address0_mutex" but no longer is due to commit 6fecd4f2a58c ("USB: separate usb_address0 mutexes for each bus") With separate buses (and locks) it is no longer the case that a single lock will protect xhci_setup_device from accesses by two parallel threads processing events on the two buses. Fix this by adding a mutex to protect addr_dev and slot_id in struct xhci_hcd, and by making the assignment of slot_id atomic. Fixes multiple boot errors: [ 0.583008] xhci_hcd 0000:00:14.0: Bad Slot ID 2 [ 0.583009] xhci_hcd 0000:00:14.0: Could not allocate xHCI USB device data structures [ 0.583012] usb usb1-port3: couldn't allocate usb_device And: [ 0.637409] xhci_hcd 0000:00:14.0: Error while assigning device slot ID [ 0.637417] xhci_hcd 0000:00:14.0: Max number of devices this xHCI host supports is 32. [ 0.637421] usb usb1-port1: couldn't allocate usb_device And: [ 0.753372] xhci_hcd 0000:00:14.0: ERROR: unexpected setup context command completion code 0x0. [ 0.753373] usb 1-3: hub failed to enable device, error -22 [ 0.753400] xhci_hcd 0000:00:14.0: Error while assigning device slot ID [ 0.753402] xhci_hcd 0000:00:14.0: Max number of devices this xHCI host supports is 32. [ 0.753403] usb usb1-port3: couldn't allocate usb_device And: [ 11.018386] usb 1-3: device descriptor read/all, error -110 And: [ 5.753838] xhci_hcd 0000:00:14.0: Timeout while waiting for setup device command Tested with 200 reboots, resulting in no USB hub init related errors. Fixes: 638139eb95d2 ("usb: hub: allow to process more usb hub events in parallel") Link: https://lkml.kernel.org/g/CAP-bSRb=A0iEYobdGCLpwynS7pkxpt_9ZnwyZTPVAoy0Y=Zo3Q@mail.gmail.com Signed-off-by: Chris Bainbridge Cc: # 3.18+ [changed git commit description style for checkpatch -Mathias] Signed-off-by: Mathias Nyman Signed-off-by: Greg Kroah-Hartman --- drivers/usb/host/xhci.c | 49 +++++++++++++++++++++++++---------------- drivers/usb/host/xhci.h | 2 ++ 2 files changed, 32 insertions(+), 19 deletions(-) diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c index 4299cbf47793..36bf089b708f 100644 --- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -3682,18 +3682,21 @@ int xhci_alloc_dev(struct usb_hcd *hcd, struct usb_device *udev) { struct xhci_hcd *xhci = hcd_to_xhci(hcd); unsigned long flags; - int ret; + int ret, slot_id; struct xhci_command *command; command = xhci_alloc_command(xhci, false, false, GFP_KERNEL); if (!command) return 0; + /* xhci->slot_id and xhci->addr_dev are not thread-safe */ + mutex_lock(&xhci->mutex); spin_lock_irqsave(&xhci->lock, flags); command->completion = &xhci->addr_dev; ret = xhci_queue_slot_control(xhci, command, TRB_ENABLE_SLOT, 0); if (ret) { spin_unlock_irqrestore(&xhci->lock, flags); + mutex_unlock(&xhci->mutex); xhci_dbg(xhci, "FIXME: allocate a command ring segment\n"); kfree(command); return 0; @@ -3702,8 +3705,10 @@ int xhci_alloc_dev(struct usb_hcd *hcd, struct usb_device *udev) spin_unlock_irqrestore(&xhci->lock, flags); wait_for_completion(command->completion); + slot_id = xhci->slot_id; + mutex_unlock(&xhci->mutex); - if (!xhci->slot_id || command->status != COMP_SUCCESS) { + if (!slot_id || command->status != COMP_SUCCESS) { xhci_err(xhci, "Error while assigning device slot ID\n"); xhci_err(xhci, "Max number of devices this xHCI host supports is %u.\n", HCS_MAX_SLOTS( @@ -3728,11 +3733,11 @@ int xhci_alloc_dev(struct usb_hcd *hcd, struct usb_device *udev) * xhci_discover_or_reset_device(), which may be called as part of * mass storage driver error handling. */ - if (!xhci_alloc_virt_device(xhci, xhci->slot_id, udev, GFP_NOIO)) { + if (!xhci_alloc_virt_device(xhci, slot_id, udev, GFP_NOIO)) { xhci_warn(xhci, "Could not allocate xHCI USB device data structures\n"); goto disable_slot; } - udev->slot_id = xhci->slot_id; + udev->slot_id = slot_id; #ifndef CONFIG_USB_DEFAULT_PERSIST /* @@ -3778,12 +3783,15 @@ static int xhci_setup_device(struct usb_hcd *hcd, struct usb_device *udev, struct xhci_slot_ctx *slot_ctx; struct xhci_input_control_ctx *ctrl_ctx; u64 temp_64; - struct xhci_command *command; + struct xhci_command *command = NULL; + + mutex_lock(&xhci->mutex); if (!udev->slot_id) { xhci_dbg_trace(xhci, trace_xhci_dbg_address, "Bad Slot ID %d", udev->slot_id); - return -EINVAL; + ret = -EINVAL; + goto out; } virt_dev = xhci->devs[udev->slot_id]; @@ -3796,7 +3804,8 @@ static int xhci_setup_device(struct usb_hcd *hcd, struct usb_device *udev, */ xhci_warn(xhci, "Virt dev invalid for slot_id 0x%x!\n", udev->slot_id); - return -EINVAL; + ret = -EINVAL; + goto out; } if (setup == SETUP_CONTEXT_ONLY) { @@ -3804,13 +3813,15 @@ static int xhci_setup_device(struct usb_hcd *hcd, struct usb_device *udev, if (GET_SLOT_STATE(le32_to_cpu(slot_ctx->dev_state)) == SLOT_STATE_DEFAULT) { xhci_dbg(xhci, "Slot already in default state\n"); - return 0; + goto out; } } command = xhci_alloc_command(xhci, false, false, GFP_KERNEL); - if (!command) - return -ENOMEM; + if (!command) { + ret = -ENOMEM; + goto out; + } command->in_ctx = virt_dev->in_ctx; command->completion = &xhci->addr_dev; @@ -3820,8 +3831,8 @@ static int xhci_setup_device(struct usb_hcd *hcd, struct usb_device *udev, if (!ctrl_ctx) { xhci_warn(xhci, "%s: Could not get input context, bad type.\n", __func__); - kfree(command); - return -EINVAL; + ret = -EINVAL; + goto out; } /* * If this is the first Set Address since device plug-in or @@ -3848,8 +3859,7 @@ static int xhci_setup_device(struct usb_hcd *hcd, struct usb_device *udev, spin_unlock_irqrestore(&xhci->lock, flags); xhci_dbg_trace(xhci, trace_xhci_dbg_address, "FIXME: allocate a command ring segment"); - kfree(command); - return ret; + goto out; } xhci_ring_cmd_db(xhci); spin_unlock_irqrestore(&xhci->lock, flags); @@ -3896,10 +3906,8 @@ static int xhci_setup_device(struct usb_hcd *hcd, struct usb_device *udev, ret = -EINVAL; break; } - if (ret) { - kfree(command); - return ret; - } + if (ret) + goto out; temp_64 = xhci_read_64(xhci, &xhci->op_regs->dcbaa_ptr); xhci_dbg_trace(xhci, trace_xhci_dbg_address, "Op regs DCBAA ptr = %#016llx", temp_64); @@ -3932,8 +3940,10 @@ static int xhci_setup_device(struct usb_hcd *hcd, struct usb_device *udev, xhci_dbg_trace(xhci, trace_xhci_dbg_address, "Internal device address = %d", le32_to_cpu(slot_ctx->dev_state) & DEV_ADDR_MASK); +out: + mutex_unlock(&xhci->mutex); kfree(command); - return 0; + return ret; } int xhci_address_device(struct usb_hcd *hcd, struct usb_device *udev) @@ -4855,6 +4865,7 @@ int xhci_gen_setup(struct usb_hcd *hcd, xhci_get_quirks_t get_quirks) return 0; } + mutex_init(&xhci->mutex); xhci->cap_regs = hcd->regs; xhci->op_regs = hcd->regs + HC_LENGTH(readl(&xhci->cap_regs->hc_capbase)); diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h index ea75e8ccd3c1..6977f8491fa7 100644 --- a/drivers/usb/host/xhci.h +++ b/drivers/usb/host/xhci.h @@ -1497,6 +1497,8 @@ struct xhci_hcd { struct list_head lpm_failed_devs; /* slot enabling and address device helpers */ + /* these are not thread safe so use mutex */ + struct mutex mutex; struct completion addr_dev; int slot_id; /* For USB 3.0 LPM enable/disable. */ -- 2.20.1