From a21d4fed4b00eaf7e7c3b2e2b25de24f540bfa66 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Tue, 29 Nov 2005 12:04:24 -0500 Subject: [PATCH] [PATCH] USB Gadget: file_storage: remove "volatile" declarations This patch (as612) removes the "volatile" declarations from the file-storage gadget. It turns out that they aren't needed for anything much; adding a few memory barriers does a sufficient job. The patch also removes a wait_queue. Not much point having a queue when only one task is ever going to be on it! Signed-off-by: Alan Stern Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/file_storage.c | 59 ++++++++++++++++++++----------- 1 file changed, 38 insertions(+), 21 deletions(-) diff --git a/drivers/usb/gadget/file_storage.c b/drivers/usb/gadget/file_storage.c index f6c49b717d..0cea9782d7 100644 --- a/drivers/usb/gadget/file_storage.c +++ b/drivers/usb/gadget/file_storage.c @@ -239,7 +239,6 @@ #include #include #include -#include #include #include @@ -251,7 +250,7 @@ #define DRIVER_DESC "File-backed Storage Gadget" #define DRIVER_NAME "g_file_storage" -#define DRIVER_VERSION "20 October 2004" +#define DRIVER_VERSION "28 November 2005" static const char longname[] = DRIVER_DESC; static const char shortname[] = DRIVER_NAME; @@ -588,7 +587,7 @@ enum fsg_buffer_state { struct fsg_buffhd { void *buf; dma_addr_t dma; - volatile enum fsg_buffer_state state; + enum fsg_buffer_state state; struct fsg_buffhd *next; /* The NetChip 2280 is faster, and handles some protocol faults @@ -597,9 +596,9 @@ struct fsg_buffhd { unsigned int bulk_out_intended_length; struct usb_request *inreq; - volatile int inreq_busy; + int inreq_busy; struct usb_request *outreq; - volatile int outreq_busy; + int outreq_busy; }; enum fsg_state { @@ -637,11 +636,11 @@ struct fsg_dev { struct usb_ep *ep0; // Handy copy of gadget->ep0 struct usb_request *ep0req; // For control responses - volatile unsigned int ep0_req_tag; + unsigned int ep0_req_tag; const char *ep0req_name; struct usb_request *intreq; // For interrupt responses - volatile int intreq_busy; + int intreq_busy; struct fsg_buffhd *intr_buffhd; unsigned int bulk_out_maxpacket; @@ -671,7 +670,6 @@ struct fsg_dev { struct fsg_buffhd *next_buffhd_to_drain; struct fsg_buffhd buffhds[NUM_BUFFERS]; - wait_queue_head_t thread_wqh; int thread_wakeup_needed; struct completion thread_notifier; struct task_struct *thread_task; @@ -1076,11 +1074,13 @@ static int populate_config_buf(struct usb_gadget *gadget, /* These routines may be called in process context or in_irq */ +/* Caller must hold fsg->lock */ static void wakeup_thread(struct fsg_dev *fsg) { /* Tell the main thread that something has happened */ fsg->thread_wakeup_needed = 1; - wake_up_all(&fsg->thread_wqh); + if (fsg->thread_task) + wake_up_process(fsg->thread_task); } @@ -1167,11 +1167,12 @@ static void bulk_in_complete(struct usb_ep *ep, struct usb_request *req) usb_ep_fifo_flush(ep); /* Hold the lock while we update the request and buffer states */ + smp_wmb(); spin_lock(&fsg->lock); bh->inreq_busy = 0; bh->state = BUF_STATE_EMPTY; - spin_unlock(&fsg->lock); wakeup_thread(fsg); + spin_unlock(&fsg->lock); } static void bulk_out_complete(struct usb_ep *ep, struct usb_request *req) @@ -1188,11 +1189,12 @@ static void bulk_out_complete(struct usb_ep *ep, struct usb_request *req) usb_ep_fifo_flush(ep); /* Hold the lock while we update the request and buffer states */ + smp_wmb(); spin_lock(&fsg->lock); bh->outreq_busy = 0; bh->state = BUF_STATE_FULL; - spin_unlock(&fsg->lock); wakeup_thread(fsg); + spin_unlock(&fsg->lock); } @@ -1209,11 +1211,12 @@ static void intr_in_complete(struct usb_ep *ep, struct usb_request *req) usb_ep_fifo_flush(ep); /* Hold the lock while we update the request and buffer states */ + smp_wmb(); spin_lock(&fsg->lock); fsg->intreq_busy = 0; bh->state = BUF_STATE_EMPTY; - spin_unlock(&fsg->lock); wakeup_thread(fsg); + spin_unlock(&fsg->lock); } #else @@ -1264,8 +1267,8 @@ static void received_cbi_adsc(struct fsg_dev *fsg, struct fsg_buffhd *bh) fsg->cbbuf_cmnd_size = req->actual; memcpy(fsg->cbbuf_cmnd, req->buf, fsg->cbbuf_cmnd_size); - spin_unlock(&fsg->lock); wakeup_thread(fsg); + spin_unlock(&fsg->lock); } #else @@ -1517,8 +1520,8 @@ static int fsg_setup(struct usb_gadget *gadget, /* Use this for bulk or interrupt transfers, not ep0 */ static void start_transfer(struct fsg_dev *fsg, struct usb_ep *ep, - struct usb_request *req, volatile int *pbusy, - volatile enum fsg_buffer_state *state) + struct usb_request *req, int *pbusy, + enum fsg_buffer_state *state) { int rc; @@ -1526,8 +1529,11 @@ static void start_transfer(struct fsg_dev *fsg, struct usb_ep *ep, dump_msg(fsg, "bulk-in", req->buf, req->length); else if (ep == fsg->intr_in) dump_msg(fsg, "intr-in", req->buf, req->length); + + spin_lock_irq(&fsg->lock); *pbusy = 1; *state = BUF_STATE_BUSY; + spin_unlock_irq(&fsg->lock); rc = usb_ep_queue(ep, req, GFP_KERNEL); if (rc != 0) { *pbusy = 0; @@ -1547,14 +1553,23 @@ static void start_transfer(struct fsg_dev *fsg, struct usb_ep *ep, static int sleep_thread(struct fsg_dev *fsg) { - int rc; + int rc = 0; /* Wait until a signal arrives or we are woken up */ - rc = wait_event_interruptible(fsg->thread_wqh, - fsg->thread_wakeup_needed); + for (;;) { + try_to_freeze(); + set_current_state(TASK_INTERRUPTIBLE); + if (signal_pending(current)) { + rc = -EINTR; + break; + } + if (fsg->thread_wakeup_needed) + break; + schedule(); + } + __set_current_state(TASK_RUNNING); fsg->thread_wakeup_needed = 0; - try_to_freeze(); - return (rc ? -EINTR : 0); + return rc; } @@ -1791,6 +1806,7 @@ static int do_write(struct fsg_dev *fsg) if (bh->state == BUF_STATE_EMPTY && !get_some_more) break; // We stopped early if (bh->state == BUF_STATE_FULL) { + smp_rmb(); fsg->next_buffhd_to_drain = bh->next; bh->state = BUF_STATE_EMPTY; @@ -2359,6 +2375,7 @@ static int throw_away_data(struct fsg_dev *fsg) /* Throw away the data in a filled buffer */ if (bh->state == BUF_STATE_FULL) { + smp_rmb(); bh->state = BUF_STATE_EMPTY; fsg->next_buffhd_to_drain = bh->next; @@ -3024,6 +3041,7 @@ static int get_next_command(struct fsg_dev *fsg) if ((rc = sleep_thread(fsg)) != 0) return rc; } + smp_rmb(); rc = received_cbw(fsg, bh); bh->state = BUF_STATE_EMPTY; @@ -4072,7 +4090,6 @@ static int __init fsg_alloc(void) spin_lock_init(&fsg->lock); init_rwsem(&fsg->filesem); kref_init(&fsg->ref); - init_waitqueue_head(&fsg->thread_wqh); init_completion(&fsg->thread_notifier); the_fsg = fsg; -- 2.39.5