linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: madhuparnabhowmik10@gmail.com
To: arnd@arndb.de, gregkh@linuxfoundation.org
Cc: linux-kernel@vger.kernel.org, andrianov@ispras.ru,
	ldv-project@linuxtesting.org,
	Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
Subject: [PATCH] drivers: char: applicom.c: Add lock for protecting DeviceErrorCount
Date: Mon,  3 Aug 2020 16:20:49 +0530	[thread overview]
Message-ID: <20200803105049.11089-1-madhuparnabhowmik10@gmail.com> (raw)

From: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>

The variable DeviceErrorCount is used to keep track of the number of
errors in read, write and interrupt routines, however it was not
protected by proper locking.
Therefore, this patch adds a spinlock: error_lock to protect the
variable.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
---
 drivers/char/applicom.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/char/applicom.c b/drivers/char/applicom.c
index 14b2d8034c51..6df7450b8b99 100644
--- a/drivers/char/applicom.c
+++ b/drivers/char/applicom.c
@@ -106,6 +106,7 @@ static DECLARE_WAIT_QUEUE_HEAD(FlagSleepRec);
 static unsigned int WriteErrorCount;	/* number of write error      */
 static unsigned int ReadErrorCount;	/* number of read error       */
 static unsigned int DeviceErrorCount;	/* number of device error     */
+DEFINE_SPINLOCK(error_lock);		/* lock to protect error count variables */
 
 static ssize_t ac_read (struct file *, char __user *, size_t, loff_t *);
 static ssize_t ac_write (struct file *, const char __user *, size_t, loff_t *);
@@ -428,7 +429,9 @@ static ssize_t ac_write(struct file *file, const char __user *buf, size_t count,
 		spin_unlock_irqrestore(&apbs[IndexCard].mutex, flags);
 		printk(KERN_WARNING "APPLICOM driver write error board %d, DataFromPcReady = %d\n",
 		       IndexCard,(int)readb(apbs[IndexCard].RamIO + DATA_FROM_PC_READY));
+		spin_lock_irqsave(&error_lock, flags);
 		DeviceErrorCount++;
+		spin_unlock_irqrestore(&error_lock, flags);
 		return -EIO;
 	}
 	
@@ -593,7 +596,9 @@ static ssize_t ac_read (struct file *filp, char __user *buf, size_t count, loff_
 				
 				printk(KERN_WARNING "APPLICOM driver read error board %d, DataToPcReady = %d\n",
 				       i,(int)readb(apbs[i].RamIO + DATA_TO_PC_READY));
+				spin_lock_irqsave(&error_lock, flags);
 				DeviceErrorCount++;
+				spin_unlock_irqrestore(&error_lock, flags);
 				return -EIO;
 			}
 			
@@ -653,7 +658,9 @@ static irqreturn_t ac_interrupt(int vec, void *dev_instance)
 			if (readb(apbs[i].RamIO + DATA_TO_PC_READY) > 2) {
 				printk(KERN_WARNING "APPLICOM driver interrupt err board %d, DataToPcReady = %d\n",
 				       i+1,(int)readb(apbs[i].RamIO + DATA_TO_PC_READY));
+				spin_lock(&error_lock);
 				DeviceErrorCount++;
+				spin_unlock(&error_lock);
 			}
 
 			if((readb(apbs[i].RamIO + DATA_FROM_PC_READY) > 2) && 
@@ -661,7 +668,9 @@ static irqreturn_t ac_interrupt(int vec, void *dev_instance)
 				
 				printk(KERN_WARNING "APPLICOM driver interrupt err board %d, DataFromPcReady = %d\n",
 				       i+1,(int)readb(apbs[i].RamIO + DATA_FROM_PC_READY));
+				spin_lock(&error_lock);
 				DeviceErrorCount++;
+				spin_unlock(&error_lock);
 			}
 
 			if (readb(apbs[i].RamIO + DATA_TO_PC_READY) == 2) {	/* mailbox sent by the card ?   */
@@ -699,6 +708,7 @@ static long ac_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
      
 {				/* @ ADG ou ATO selon le cas */
 	int i;
+	unsigned long flags;
 	unsigned char IndexCard;
 	void __iomem *pmem;
 	int ret = 0;
@@ -819,12 +829,14 @@ static long ac_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 			else
 				printk("\n");
 		}
+		spin_lock_irqsave(&error_lock, flags);
 		if (DeviceErrorCount != 0)
 			printk(KERN_INFO "DeviceErrorCount ........... %d\n", DeviceErrorCount);
 		if (ReadErrorCount != 0)
 			printk(KERN_INFO "ReadErrorCount ............. %d\n", ReadErrorCount);
 		if (WriteErrorCount != 0)
 			printk(KERN_INFO "WriteErrorCount ............ %d\n", WriteErrorCount);
+		spin_unlock_irqrestore(&error_lock, flags);
 		if (waitqueue_active(&FlagSleepRec))
 			printk(KERN_INFO "Process in read pending\n");
 		for (i = 0; i < MAX_BOARD; i++) {
-- 
2.17.1


             reply	other threads:[~2020-08-03 10:51 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-03 10:50 madhuparnabhowmik10 [this message]
2020-08-03 11:53 ` Greg KH
2020-08-03 22:50   ` Madhuparna Bhowmik

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200803105049.11089-1-madhuparnabhowmik10@gmail.com \
    --to=madhuparnabhowmik10@gmail.com \
    --cc=andrianov@ispras.ru \
    --cc=arnd@arndb.de \
    --cc=gregkh@linuxfoundation.org \
    --cc=ldv-project@linuxtesting.org \
    --cc=linux-kernel@vger.kernel.org \
    --subject='Re: [PATCH] drivers: char: applicom.c: Add lock for protecting DeviceErrorCount' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).