diff options
author | patacongo <patacongo@42af7a65-404d-4744-a932-0658087f49c3> | 2011-01-09 02:15:30 +0000 |
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committer | patacongo <patacongo@42af7a65-404d-4744-a932-0658087f49c3> | 2011-01-09 02:15:30 +0000 |
commit | e29ce8c2602d6d15a9ff92707ed1c7fabeb59cbe (patch) | |
tree | 313a4179d82f3351018de6ea818ea8622cbbd3c3 /nuttx/drivers/usbhost/usbhost_storage.c | |
parent | a4298bd439dfe30019734fa6e6e1558b2f8b1e02 (diff) | |
download | px4-nuttx-e29ce8c2602d6d15a9ff92707ed1c7fabeb59cbe.tar.gz px4-nuttx-e29ce8c2602d6d15a9ff92707ed1c7fabeb59cbe.tar.bz2 px4-nuttx-e29ce8c2602d6d15a9ff92707ed1c7fabeb59cbe.zip |
Fix misc race conditions and use of stale pointer
git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3234 42af7a65-404d-4744-a932-0658087f49c3
Diffstat (limited to 'nuttx/drivers/usbhost/usbhost_storage.c')
-rw-r--r-- | nuttx/drivers/usbhost/usbhost_storage.c | 380 |
1 files changed, 255 insertions, 125 deletions
diff --git a/nuttx/drivers/usbhost/usbhost_storage.c b/nuttx/drivers/usbhost/usbhost_storage.c index 680e21569..7aee9d2ea 100644 --- a/nuttx/drivers/usbhost/usbhost_storage.c +++ b/nuttx/drivers/usbhost/usbhost_storage.c @@ -120,16 +120,17 @@ struct usbhost_state_s /* The remainder of the fields are provide o the mass storage class */ - char sdchar; /* Character identifying the /dev/sd[n] device */ - int16_t crefs; /* Reference count on the driver instance */ - uint16_t blocksize; /* Block size of USB mass storage device */ - uint32_t nblocks; /* Number of blocks on the USB mass storage device */ - sem_t exclsem; /* Used to maintain mutual exclusive access */ - struct work_s work; /* For interacting with the worker thread */ - FAR uint8_t *tdbuffer; /* The allocated transfer descriptor buffer */ - size_t tdbuflen; /* Size of the allocated transfer buffer */ - struct usbhost_epdesc_s bulkin; /* Bulk IN endpoint */ - struct usbhost_epdesc_s bulkout; /* Bulk OUT endpoint */ + char sdchar; /* Character identifying the /dev/sd[n] device */ + volatile bool disconnected; /* TRUE: Device has been disconnected */ + int16_t crefs; /* Reference count on the driver instance */ + uint16_t blocksize; /* Block size of USB mass storage device */ + uint32_t nblocks; /* Number of blocks on the USB mass storage device */ + sem_t exclsem; /* Used to maintain mutual exclusive access */ + struct work_s work; /* For interacting with the worker thread */ + FAR uint8_t *tdbuffer; /* The allocated transfer descriptor buffer */ + size_t tdbuflen; /* Size of the allocated transfer buffer */ + struct usbhost_epdesc_s bulkin; /* Bulk IN endpoint */ + struct usbhost_epdesc_s bulkout; /* Bulk OUT endpoint */ }; /**************************************************************************** @@ -143,8 +144,8 @@ static void usbhost_takesem(sem_t *sem); /* Memory allocation services */ -static inline struct usbhost_state_s *usbhost_allocclass(void); -static inline void usbhost_freeclass(struct usbhost_state_s *class); +static inline FAR struct usbhost_state_s *usbhost_allocclass(void); +static inline void usbhost_freeclass(FAR struct usbhost_state_s *class); /* Device name management */ @@ -342,7 +343,7 @@ static void usbhost_takesem(sem_t *sem) ****************************************************************************/ #if CONFIG_USBHOST_NPREALLOC > 0 -static inline struct usbhost_state_s *usbhost_allocclass(void) +static inline FAR struct usbhost_state_s *usbhost_allocclass(void) { struct usbhost_state_s *priv; irqstate_t flags; @@ -359,17 +360,22 @@ static inline struct usbhost_state_s *usbhost_allocclass(void) priv->class.flink = NULL; } irqrestore(flags); + ullvdbg("Allocated: %p\n", priv);; return priv; } #else -static inline struct usbhost_state_s *usbhost_allocclass(void) +static inline FAR struct usbhost_state_s *usbhost_allocclass(void) { + FAR struct usbhost_state_s *priv; + /* We are not executing from an interrupt handler so we can just call * malloc() to get memory for the class instance. */ DEBUGASSERT(!up_interrupt_context()); - return (struct usbhost_state_s *)malloc(sizeof(struct usbhost_state_s)); + priv = (FAR struct usbhost_state_s *)malloc(sizeof(struct usbhost_state_s)); + uvdbg("Allocated: %p\n", priv);; + return priv; } #endif @@ -388,11 +394,13 @@ static inline struct usbhost_state_s *usbhost_allocclass(void) ****************************************************************************/ #if CONFIG_USBHOST_NPREALLOC > 0 -static inline void usbhost_freeclass(struct usbhost_state_s *class) +static inline void usbhost_freeclass(FAR struct usbhost_state_s *class) { irqstate_t flags; DEBUGASSERT(class != NULL); + ullvdbg("Freeing: %p\n", class);; + /* Just put the pre-allocated class structure back on the freelist */ flags = irqsave(); @@ -401,7 +409,7 @@ static inline void usbhost_freeclass(struct usbhost_state_s *class) irqrestore(flags); } #else -static inline void usbhost_freeclass(struct usbhost_state_s *class) +static inline void usbhost_freeclass(FAR struct usbhost_state_s *class) { DEBUGASSERT(class != NULL); @@ -409,6 +417,7 @@ static inline void usbhost_freeclass(struct usbhost_state_s *class) * from an interrupt handler. */ + uvdbg("Freeing: %p\n", class);; free(class); } #endif @@ -651,44 +660,63 @@ static inline int usbhost_maxlunreq(FAR struct usbhost_state_s *priv) FAR struct usb_ctrlreq_s *req = (FAR struct usb_ctrlreq_s *)priv->tdbuffer; DEBUGASSERT(priv && priv->tdbuffer); - /* Request maximum logical unit number. NOTE: On an IN transaction, The - * req and buffer pointers passed to DRVR_CTRLIN may refer to the same - * allocated memory. - */ + /* Make sure that the device is still connected. */ - uvdbg("Request maximum logical unit number\n"); - memset(req, 0, sizeof(struct usb_ctrlreq_s)); - req->type = USB_DIR_IN|USB_REQ_TYPE_CLASS|USB_REQ_RECIPIENT_INTERFACE; - req->req = USBSTRG_REQ_GETMAXLUN; - usbhost_putle16(req->len, 1); - return DRVR_CTRLIN(priv->drvr, req, priv->tdbuffer); + if (!priv->disconnected) + { + /* Request maximum logical unit number. NOTE: On an IN transaction, The + * req and buffer pointers passed to DRVR_CTRLIN may refer to the same + * allocated memory. + */ + + uvdbg("Request maximum logical unit number\n"); + memset(req, 0, sizeof(struct usb_ctrlreq_s)); + req->type = USB_DIR_IN|USB_REQ_TYPE_CLASS|USB_REQ_RECIPIENT_INTERFACE; + req->req = USBSTRG_REQ_GETMAXLUN; + usbhost_putle16(req->len, 1); + return DRVR_CTRLIN(priv->drvr, req, priv->tdbuffer); + } + + udbg("ERROR: No longer connected\n"); + return -ENODEV; } static inline int usbhost_testunitready(FAR struct usbhost_state_s *priv) { FAR struct usbstrg_cbw_s *cbw; - int result = -ENOMEM; + int result; + + /* Make sure that the device is still connected */ + + if (priv->disconnected) + { + udbg("ERROR: No longer connected\n"); + return -ENODEV; + } /* Initialize a CBW (re-using the allocated transfer buffer) */ cbw = usbhost_cbwalloc(priv); - if (cbw) + if (!cbw) { - /* Construct and send the CBW */ + udbg("ERROR: Failed to create CBW\n"); + return -ENOMEM; + } + + /* Construct and send the CBW */ - usbhost_testunitreadycbw(cbw); - result = DRVR_TRANSFER(priv->drvr, &priv->bulkout, - (uint8_t*)cbw, USBSTRG_CBW_SIZEOF); + usbhost_testunitreadycbw(cbw); + result = DRVR_TRANSFER(priv->drvr, &priv->bulkout, + (uint8_t*)cbw, USBSTRG_CBW_SIZEOF); + if (result == OK) + { + /* Receive the CSW */ + + result = DRVR_TRANSFER(priv->drvr, &priv->bulkin, + priv->tdbuffer, USBSTRG_CSW_SIZEOF); if (result == OK) { - /* Receive the CSW */ - - result = DRVR_TRANSFER(priv->drvr, &priv->bulkin, - priv->tdbuffer, USBSTRG_CSW_SIZEOF); - if (result == OK) - { - usbhost_dumpcsw((FAR struct usbstrg_csw_s *)priv->tdbuffer); - } + usbhost_dumpcsw((FAR struct usbstrg_csw_s *)priv->tdbuffer); } } return result; @@ -697,37 +725,49 @@ static inline int usbhost_testunitready(FAR struct usbhost_state_s *priv) static inline int usbhost_requestsense(FAR struct usbhost_state_s *priv) { FAR struct usbstrg_cbw_s *cbw; - int result = -ENOMEM; + int result; + + /* Make sure that the device is still connected */ + + if (priv->disconnected) + { + udbg("ERROR: No longer connected\n"); + return -ENODEV; + } /* Initialize a CBW (re-using the allocated transfer buffer) */ cbw = usbhost_cbwalloc(priv); - if (cbw) + if (!cbw) { - /* Construct and send the CBW */ + udbg("ERROR: Failed to create CBW\n"); + return -ENOMEM; + } + + /* Construct and send the CBW */ - usbhost_requestsensecbw(cbw); - result = DRVR_TRANSFER(priv->drvr, &priv->bulkout, - (uint8_t*)cbw, USBSTRG_CBW_SIZEOF); + usbhost_requestsensecbw(cbw); + result = DRVR_TRANSFER(priv->drvr, &priv->bulkout, + (uint8_t*)cbw, USBSTRG_CBW_SIZEOF); + if (result == OK) + { + /* Receive the sense data response */ + + result = DRVR_TRANSFER(priv->drvr, &priv->bulkin, + priv->tdbuffer, SCSIRESP_FIXEDSENSEDATA_SIZEOF); if (result == OK) { - /* Receive the sense data response */ + /* Receive the CSW */ result = DRVR_TRANSFER(priv->drvr, &priv->bulkin, - priv->tdbuffer, SCSIRESP_FIXEDSENSEDATA_SIZEOF); + priv->tdbuffer, USBSTRG_CSW_SIZEOF); if (result == OK) { - /* Receive the CSW */ - - result = DRVR_TRANSFER(priv->drvr, &priv->bulkin, - priv->tdbuffer, USBSTRG_CSW_SIZEOF); - if (result == OK) - { - usbhost_dumpcsw((FAR struct usbstrg_csw_s *)priv->tdbuffer); - } + usbhost_dumpcsw((FAR struct usbstrg_csw_s *)priv->tdbuffer); } } } + return result; } @@ -735,43 +775,55 @@ static inline int usbhost_readcapacity(FAR struct usbhost_state_s *priv) { FAR struct usbstrg_cbw_s *cbw; FAR struct scsiresp_readcapacity10_s *resp; - int result = -ENOMEM; + int result; + + /* Make sure that the device is still connected */ + + if (priv->disconnected) + { + udbg("ERROR: No longer connected\n"); + return -ENODEV; + } /* Initialize a CBW (re-using the allocated transfer buffer) */ cbw = usbhost_cbwalloc(priv); - if (cbw) + if (!cbw) { - /* Construct and send the CBW */ + udbg("ERROR: Failed to create CBW\n"); + return -ENOMEM; + } + + /* Construct and send the CBW */ - usbhost_readcapacitycbw(cbw); - result = DRVR_TRANSFER(priv->drvr, &priv->bulkout, - (uint8_t*)cbw, USBSTRG_CBW_SIZEOF); + usbhost_readcapacitycbw(cbw); + result = DRVR_TRANSFER(priv->drvr, &priv->bulkout, + (uint8_t*)cbw, USBSTRG_CBW_SIZEOF); + if (result == OK) + { + /* Receive the read capacity CBW IN response */ + + result = DRVR_TRANSFER(priv->drvr, &priv->bulkin, + priv->tdbuffer, SCSIRESP_READCAPACITY10_SIZEOF); if (result == OK) { - /* Receive the read capacity CBW IN response */ + /* Save the capacity information */ + + resp = (FAR struct scsiresp_readcapacity10_s *)priv->tdbuffer; + priv->nblocks = usbhost_getbe32(resp->lba); + priv->blocksize = usbhost_getbe32(resp->blklen); + + /* Receive the CSW */ result = DRVR_TRANSFER(priv->drvr, &priv->bulkin, - priv->tdbuffer, SCSIRESP_READCAPACITY10_SIZEOF); + priv->tdbuffer, USBSTRG_CSW_SIZEOF); if (result == OK) { - /* Save the capacity information */ - - resp = (FAR struct scsiresp_readcapacity10_s *)priv->tdbuffer; - priv->nblocks = usbhost_getbe32(resp->lba); - priv->blocksize = usbhost_getbe32(resp->blklen); - - /* Receive the CSW */ - - result = DRVR_TRANSFER(priv->drvr, &priv->bulkin, - priv->tdbuffer, USBSTRG_CSW_SIZEOF); - if (result == OK) - { - usbhost_dumpcsw((FAR struct usbstrg_csw_s *)priv->tdbuffer); - } + usbhost_dumpcsw((FAR struct usbstrg_csw_s *)priv->tdbuffer); } } } + return result; } @@ -779,41 +831,53 @@ static inline int usbhost_inquiry(FAR struct usbhost_state_s *priv) { FAR struct usbstrg_cbw_s *cbw; FAR struct scsiresp_inquiry_s *resp; - int result = -ENOMEM; + int result; + + /* Make sure that the device is still connected */ + + if (priv->disconnected) + { + udbg("ERROR: No longer connected\n"); + return -ENODEV; + } /* Initialize a CBW (re-using the allocated transfer buffer) */ cbw = usbhost_cbwalloc(priv); - if (cbw) + if (!cbw) { - /* Construct and send the CBW */ + udbg("ERROR: Failed to create CBW\n"); + return -ENOMEM; + } + + /* Construct and send the CBW */ - usbhost_inquirycbw(cbw); - result = DRVR_TRANSFER(priv->drvr, &priv->bulkout, - (uint8_t*)cbw, USBSTRG_CBW_SIZEOF); + usbhost_inquirycbw(cbw); + result = DRVR_TRANSFER(priv->drvr, &priv->bulkout, + (uint8_t*)cbw, USBSTRG_CBW_SIZEOF); + if (result == OK) + { + /* Receive the CBW IN response */ + + result = DRVR_TRANSFER(priv->drvr, &priv->bulkin, + priv->tdbuffer, SCSIRESP_INQUIRY_SIZEOF); if (result == OK) { - /* Receive the CBW IN response */ + /* TODO: If USB debug is enabled, dump the response data here */ + + resp = (FAR struct scsiresp_inquiry_s *)priv->tdbuffer; + + /* Receive the CSW */ result = DRVR_TRANSFER(priv->drvr, &priv->bulkin, - priv->tdbuffer, SCSIRESP_INQUIRY_SIZEOF); + priv->tdbuffer, USBSTRG_CSW_SIZEOF); if (result == OK) { - /* TODO: If USB debug is enabled, dump the response data here */ - - resp = (FAR struct scsiresp_inquiry_s *)priv->tdbuffer; - - /* Receive the CSW */ - - result = DRVR_TRANSFER(priv->drvr, &priv->bulkin, - priv->tdbuffer, USBSTRG_CSW_SIZEOF); - if (result == OK) - { - usbhost_dumpcsw((FAR struct usbstrg_csw_s *)priv->tdbuffer); - } + usbhost_dumpcsw((FAR struct usbstrg_csw_s *)priv->tdbuffer); } } } + return result; } @@ -839,6 +903,7 @@ static void usbhost_destroy(FAR void *arg) char devname[DEV_NAMELEN]; DEBUGASSERT(priv != NULL); + uvdbg("crefs: %d\n", priv->crefs); /* Unregister the block driver */ @@ -857,8 +922,14 @@ static void usbhost_destroy(FAR void *arg) sem_destroy(&priv->exclsem); + /* Disconnect the USB host device */ + + DRVR_DISCONNECT(priv->drvr); + /* And free the class instance. Hmmm.. this may execute on the worker - * thread and the work structure is part of what is getting freed. + * thread and the work structure is part of what is getting freed. That + * should be okay because once the work contained is removed from the + * queue, it should not longer be accessed by the worker thread. */ usbhost_freeclass(priv); @@ -898,10 +969,17 @@ static void usbhost_initvolume(FAR void *arg) result = usbhost_tdalloc(priv); if (result != OK) { - udbg("Failed to allocate transfer buffer\n"); + udbg("ERROR: Failed to allocate transfer buffer\n"); return; } + /* Increment the reference count. This will prevent usbhost_destroy() from + * being called asynchronously if the device is removed. + */ + + priv->crefs++; + DEBUGASSERT(priv->crefs == 2); + /* Request the maximum logical unit number */ uvdbg("Get max LUN\n"); @@ -959,7 +1037,7 @@ static void usbhost_initvolume(FAR void *arg) csw = (FAR struct usbstrg_csw_s *)priv->tdbuffer; if (csw->status != 0) { - udbg("CSW status error: %d\n", csw->status); + udbg("ERROR: CSW status error: %d\n", csw->status); result = -ENODEV; } } @@ -980,7 +1058,7 @@ static void usbhost_initvolume(FAR void *arg) csw = (FAR struct usbstrg_csw_s *)priv->tdbuffer; if (csw->status != 0) { - udbg("CSW status error: %d\n", csw->status); + udbg("ERROR: CSW status error: %d\n", csw->status); result = -ENODEV; } } @@ -997,18 +1075,45 @@ static void usbhost_initvolume(FAR void *arg) result = register_blockdriver(devname, &g_bops, 0, priv); } - /* Check if we successfully initialized */ + /* Check if we successfully initialized. We now have to be concerned + * about asynchronous modification of crefs because the block + * driver has been registerd. + */ if (result == OK) { - /* Ready for normal operation as a block device driver */ + usbhost_takesem(&priv->exclsem); + DEBUGASSERT(priv->crefs >= 2); + + /* Handle a corner case where (1) open() has been called so the + * reference count is > 2, but the device has been disconnected. + * In this case, the class instance needs to persist until close() + * is called. + */ - uvdbg("Successfully initialized\n"); + if (priv->crefs <= 2 && priv->disconnected) + { + /* We don't have to give the semaphore because it will be + * destroyed when usb_destroy is called. + */ + + result = -ENODEV; + } + else + { + /* Ready for normal operation as a block device driver */ + + uvdbg("Successfully initialized\n"); + priv->crefs--; + usbhost_givesem(&priv->exclsem); + } } - else + + /* Disconnect on any errors detected during volume initialization */ + + if (result != OK) { udbg("ERROR! Aborting: %d\n", result); - DRVR_DISCONNECT(priv->drvr); usbhost_destroy(priv); } } @@ -1040,6 +1145,8 @@ static void usbhost_work(FAR struct usbhost_state_s *priv, worker_t worker) * prevent us from over-running the work structure. */ + uvdbg("Queuing work: worker %p->%p\n", priv->work.worker, worker); + DEBUGASSERT(priv->work.worker == NULL); (void)work_queue(&priv->work, worker, priv, 0); } else @@ -1258,12 +1365,16 @@ static inline int usbhost_tdalloc(FAR struct usbhost_state_s *priv) static inline int usbhost_tdfree(FAR struct usbhost_state_s *priv) { - int result; - DEBUGASSERT(priv && priv->tdbuffer != NULL); + int result = OK; + DEBUGASSERT(priv); - result = DRVR_FREE(priv->drvr, priv->tdbuffer); - priv->tdbuffer = NULL; - priv->tdbuflen = 0; + if (priv->tdbuffer) + { + DEBUGASSERT(priv->drvr); + result = DRVR_FREE(priv->drvr, priv->tdbuffer); + priv->tdbuffer = NULL; + priv->tdbuflen = 0; + } return result; } @@ -1594,8 +1705,8 @@ static int usbhost_disconnected(struct usbhost_class_s *class) * of the mass storage device that the device is no longer available. */ - flags = irqsave(); - priv->drvr = NULL; + flags = irqsave(); + priv->disconnected = true; /* Now check the number of references on the class instance. If it is one, * then we can free the class instance now. Otherwise, we will have to @@ -1603,6 +1714,7 @@ static int usbhost_disconnected(struct usbhost_class_s *class) * block driver. */ + ullvdbg("crefs: %d\n", priv->crefs); if (priv->crefs == 1) { /* Destroy the class instance */ @@ -1626,15 +1738,25 @@ static int usbhost_disconnected(struct usbhost_class_s *class) static int usbhost_open(FAR struct inode *inode) { FAR struct usbhost_state_s *priv; + irqstate_t flags; int ret; uvdbg("Entry\n"); DEBUGASSERT(inode && inode->i_private); priv = (FAR struct usbhost_state_s *)inode->i_private; - /* Check if the mass storage device is still connected */ + /* Make sure that we have exclusive access to the private data structure */ + + DEBUGASSERT(priv->crefs > 0 && priv->crefs < USBHOST_MAX_CREFS); + usbhost_takesem(&priv->exclsem); + + /* Check if the mass storage device is still connected. We need to disable + * interrupts momentarily to assure that there are no asynchronous disconnect + * events. + */ - if (!priv->drvr) + flags = irqsave(); + if (priv->disconnected) { /* No... the block driver is no longer bound to the class. That means that * the USB storage device is no longer connected. Refuse any further @@ -1647,13 +1769,12 @@ static int usbhost_open(FAR struct inode *inode) { /* Otherwise, just increment the reference count on the driver */ - DEBUGASSERT(priv->crefs > 0 && priv->crefs < USBHOST_MAX_CREFS); - usbhost_takesem(&priv->exclsem); priv->crefs++; - usbhost_givesem(&priv->exclsem); ret = OK; } + irqrestore(flags); + usbhost_givesem(&priv->exclsem); return ret; } @@ -1667,6 +1788,7 @@ static int usbhost_open(FAR struct inode *inode) static int usbhost_close(FAR struct inode *inode) { FAR struct usbhost_state_s *priv; + irqstate_t flags; uvdbg("Entry\n"); DEBUGASSERT(inode && inode->i_private); @@ -1685,19 +1807,27 @@ static int usbhost_close(FAR struct inode *inode) usbhost_givesem(&priv->exclsem); + /* We need to disable interrupts momentarily to assure that there are + * no asynchronous disconnect events. + */ + + flags = irqsave(); + /* Check if the USB mass storage device is still connected. If the * storage device is not connected and the reference count just * decremented to one, then unregister the block driver and free * the class instance. */ - if (priv->crefs <= 1 && priv->drvr == NULL) + if (priv->crefs <= 1 && priv->disconnected) { /* Destroy the class instance */ DEBUGASSERT(priv->crefs == 1); usbhost_destroy(priv); } + + irqrestore(flags); return OK; } @@ -1724,7 +1854,7 @@ static ssize_t usbhost_read(FAR struct inode *inode, unsigned char *buffer, /* Check if the mass storage device is still connected */ - if (!priv->drvr) + if (priv->disconnected) { /* No... the block driver is no longer bound to the class. That means that * the USB storage device is no longer connected. Refuse any attempt to read @@ -1816,7 +1946,7 @@ static ssize_t usbhost_write(FAR struct inode *inode, const unsigned char *buffe /* Check if the mass storage device is still connected */ - if (!priv->drvr) + if (priv->disconnected) { /* No... the block driver is no longer bound to the class. That means that * the USB storage device is no longer connected. Refuse any attempt to @@ -1904,7 +2034,7 @@ static int usbhost_geometry(FAR struct inode *inode, struct geometry *geometry) /* Check if the mass storage device is still connected */ priv = (FAR struct usbhost_state_s *)inode->i_private; - if (!priv->drvr) + if (priv->disconnected) { /* No... the block driver is no longer bound to the class. That means that * the USB storage device is no longer connected. Refuse to return any @@ -1957,7 +2087,7 @@ static int usbhost_ioctl(FAR struct inode *inode, int cmd, unsigned long arg) /* Check if the mass storage device is still connected */ - if (!priv->drvr) + if (priv->disconnected) { /* No... the block driver is no longer bound to the class. That means that * the USB storage device is no longer connected. Refuse to process any |