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Commit a0040a13 authored by Manoj Prabhu B's avatar Manoj Prabhu B
Browse files

diag: Synchronize USB notifications handling event queues 



Possible race conditions while handling USB notifications in event
queues is prevented using spinlock to synchronize the list access.

Change-Id: I91bff76b6134e600b0a7091d9576089226b1629c
Signed-off-by: default avatarManoj Prabhu B <bmanoj@codeaurora.org>
parent f7be1951

drivers/char/diag/diag_usb.c

+26 −7
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-only

/* Copyright (c) 2014-2019, The Linux Foundation. All rights reserved.

/* Copyright (c) 2014-2020, The Linux Foundation. All rights reserved.

 */



#include <linux/slab.h>
@@ -232,15 +232,23 @@ static void usb_event_work_fn(struct work_struct *work) 
	struct diag_usb_info *ch = container_of(work, struct diag_usb_info,

						event_work);

	struct diag_usb_event_q *entry = NULL;

	unsigned long flags;



	if (!ch)

		return;

	spin_lock_irqsave(&ch->event_lock, flags);

	entry = list_first_entry(&(ch->event_q), struct diag_usb_event_q, link);

	if (!entry)

	if (!entry) {

		spin_unlock_irqrestore(&ch->event_lock, flags);

		return;

	}



	switch (entry->data) {

	case USB_DIAG_CONNECT:



		diag_usb_event_remove(entry);

		spin_unlock_irqrestore(&ch->event_lock, flags);



		wait_event_interruptible(ch->wait_q, ch->enabled > 0);

		ch->max_size = usb_diag_request_size(ch->hdl);

		atomic_set(&ch->connected, 1);
@@ -252,6 +260,10 @@ static void usb_event_work_fn(struct work_struct *work) 
		usb_connect(ch);

		break;

	case USB_DIAG_DISCONNECT:



		diag_usb_event_remove(entry);

		spin_unlock_irqrestore(&ch->event_lock, flags);



		atomic_set(&ch->connected, 0);

		DIAG_LOG(DIAG_DEBUG_PERIPHERALS,

		"diag: USB channel %s: Cleared connected(%d) status\n",
@@ -264,8 +276,11 @@ static void usb_event_work_fn(struct work_struct *work) 


		usb_disconnect(ch);

		break;

	default:

		spin_unlock_irqrestore(&ch->event_lock, flags);

		break;

	}

	diag_usb_event_remove(entry);



	if (!list_empty(&ch->event_q))

		queue_work(ch->usb_wq, &(ch->event_work));
@@ -363,8 +378,7 @@ static void diag_usb_write_done(struct diag_usb_info *ch, 
		spin_unlock_irqrestore(&ch->write_lock, flags);

		return;

	}

	DIAG_LOG(DIAG_DEBUG_MUX, "full write_done, ctxt: %d\n",

		 ctxt);

	DIAG_LOG(DIAG_DEBUG_MUX, "full write_done\n");

	list_del(&entry->track);

	ctxt = entry->ctxt;

	buf = entry->buf;
@@ -398,7 +412,9 @@ static void diag_usb_notifier(void *priv, unsigned int event, 
		DIAG_LOG(DIAG_DEBUG_PERIPHERALS,

			"diag: USB channel %s: Received Connect event\n",

			usb_info->name);

		spin_lock_irqsave(&usb_info->event_lock, flags);

		diag_usb_event_add(usb_info, USB_DIAG_CONNECT);

		spin_unlock_irqrestore(&usb_info->event_lock, flags);

		queue_work(usb_info->usb_wq,

			   &usb_info->event_work);

		break;
@@ -406,7 +422,9 @@ static void diag_usb_notifier(void *priv, unsigned int event, 
		DIAG_LOG(DIAG_DEBUG_PERIPHERALS,

			"diag: USB channel %s: Received Disconnect event\n",

			usb_info->name);

		spin_lock_irqsave(&usb_info->event_lock, flags);

		diag_usb_event_add(usb_info, USB_DIAG_DISCONNECT);

		spin_unlock_irqrestore(&usb_info->event_lock, flags);

		queue_work(usb_info->usb_wq,

			   &usb_info->event_work);

		break;
@@ -680,6 +698,7 @@ int diag_usb_register(int id, int ctxt, struct diag_mux_ops *ops) 
	ch->ctxt = ctxt;

	spin_lock_init(&ch->lock);

	spin_lock_init(&ch->write_lock);

	spin_lock_init(&ch->event_lock);

	ch->read_buf = kzalloc(USB_MAX_OUT_BUF, GFP_KERNEL);

	if (!ch->read_buf)

		goto err;

drivers/char/diag/diag_usb.h

+2 −1
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

/* Copyright (c) 2014-2019, The Linux Foundation. All rights reserved.

/* Copyright (c) 2014-2020, The Linux Foundation. All rights reserved.

 */



#ifndef DIAGUSB_H
@@ -58,6 +58,7 @@ struct diag_usb_info { 
	unsigned long write_cnt;

	spinlock_t lock;

	spinlock_t write_lock;

	spinlock_t event_lock;

	struct usb_diag_ch *hdl;

	struct diag_mux_ops *ops;

	unsigned char *read_buf;