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authorliu chuansheng <chuansheng.liu@intel.com>2012-07-06 09:50:08 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-07-06 09:50:08 -0700
commit5c53d819c71c63fdc91f30a59164583f68e2d63a (patch)
treee54c65ff9106c7ac29e9636310722db9d7bb170f /kernel/printk.c
parent6887a4131da3adaab011613776d865f4bcfb5678 (diff)
downloadlinux-5c53d819c71c63fdc91f30a59164583f68e2d63a.tar.gz
printk: replacing the raw_spin_lock/unlock with raw_spin_lock/unlock_irq
In function devkmsg_read/writev/llseek/poll/open()..., the function raw_spin_lock/unlock is used, there is potential deadlock case happening. CPU1: thread1 doing the cat /dev/kmsg: raw_spin_lock(&logbuf_lock); while (user->seq == log_next_seq) { when thread1 run here, at this time one interrupt is coming on CPU1 and running based on this thread,if the interrupt handle called the printk which need the logbuf_lock spin also, it will cause deadlock. So we should use raw_spin_lock/unlock_irq here. Acked-by: Kay Sievers <kay@vrfy.org> Signed-off-by: liu chuansheng <chuansheng.liu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel/printk.c')
-rw-r--r--kernel/printk.c24
1 files changed, 12 insertions, 12 deletions
diff --git a/kernel/printk.c b/kernel/printk.c
index dba18211685..12886cd19cd 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -430,20 +430,20 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
ret = mutex_lock_interruptible(&user->lock);
if (ret)
return ret;
- raw_spin_lock(&logbuf_lock);
+ raw_spin_lock_irq(&logbuf_lock);
while (user->seq == log_next_seq) {
if (file->f_flags & O_NONBLOCK) {
ret = -EAGAIN;
- raw_spin_unlock(&logbuf_lock);
+ raw_spin_unlock_irq(&logbuf_lock);
goto out;
}
- raw_spin_unlock(&logbuf_lock);
+ raw_spin_unlock_irq(&logbuf_lock);
ret = wait_event_interruptible(log_wait,
user->seq != log_next_seq);
if (ret)
goto out;
- raw_spin_lock(&logbuf_lock);
+ raw_spin_lock_irq(&logbuf_lock);
}
if (user->seq < log_first_seq) {
@@ -451,7 +451,7 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
user->idx = log_first_idx;
user->seq = log_first_seq;
ret = -EPIPE;
- raw_spin_unlock(&logbuf_lock);
+ raw_spin_unlock_irq(&logbuf_lock);
goto out;
}
@@ -501,7 +501,7 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
user->idx = log_next(user->idx);
user->seq++;
- raw_spin_unlock(&logbuf_lock);
+ raw_spin_unlock_irq(&logbuf_lock);
if (len > count) {
ret = -EINVAL;
@@ -528,7 +528,7 @@ static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence)
if (offset)
return -ESPIPE;
- raw_spin_lock(&logbuf_lock);
+ raw_spin_lock_irq(&logbuf_lock);
switch (whence) {
case SEEK_SET:
/* the first record */
@@ -552,7 +552,7 @@ static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence)
default:
ret = -EINVAL;
}
- raw_spin_unlock(&logbuf_lock);
+ raw_spin_unlock_irq(&logbuf_lock);
return ret;
}
@@ -566,14 +566,14 @@ static unsigned int devkmsg_poll(struct file *file, poll_table *wait)
poll_wait(file, &log_wait, wait);
- raw_spin_lock(&logbuf_lock);
+ raw_spin_lock_irq(&logbuf_lock);
if (user->seq < log_next_seq) {
/* return error when data has vanished underneath us */
if (user->seq < log_first_seq)
ret = POLLIN|POLLRDNORM|POLLERR|POLLPRI;
ret = POLLIN|POLLRDNORM;
}
- raw_spin_unlock(&logbuf_lock);
+ raw_spin_unlock_irq(&logbuf_lock);
return ret;
}
@@ -597,10 +597,10 @@ static int devkmsg_open(struct inode *inode, struct file *file)
mutex_init(&user->lock);
- raw_spin_lock(&logbuf_lock);
+ raw_spin_lock_irq(&logbuf_lock);
user->idx = log_first_idx;
user->seq = log_first_seq;
- raw_spin_unlock(&logbuf_lock);
+ raw_spin_unlock_irq(&logbuf_lock);
file->private_data = user;
return 0;