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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>
This commit is contained in:
parent
6887a4131d
commit
5c53d819c7
1 changed files with 12 additions and 12 deletions
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@ -430,20 +430,20 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
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ret = mutex_lock_interruptible(&user->lock);
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if (ret)
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return ret;
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raw_spin_lock(&logbuf_lock);
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raw_spin_lock_irq(&logbuf_lock);
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while (user->seq == log_next_seq) {
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if (file->f_flags & O_NONBLOCK) {
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ret = -EAGAIN;
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raw_spin_unlock(&logbuf_lock);
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raw_spin_unlock_irq(&logbuf_lock);
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goto out;
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}
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raw_spin_unlock(&logbuf_lock);
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raw_spin_unlock_irq(&logbuf_lock);
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ret = wait_event_interruptible(log_wait,
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user->seq != log_next_seq);
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if (ret)
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goto out;
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raw_spin_lock(&logbuf_lock);
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raw_spin_lock_irq(&logbuf_lock);
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}
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if (user->seq < log_first_seq) {
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@ -451,7 +451,7 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
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user->idx = log_first_idx;
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user->seq = log_first_seq;
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ret = -EPIPE;
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raw_spin_unlock(&logbuf_lock);
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raw_spin_unlock_irq(&logbuf_lock);
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goto out;
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}
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@ -501,7 +501,7 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
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user->idx = log_next(user->idx);
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user->seq++;
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raw_spin_unlock(&logbuf_lock);
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raw_spin_unlock_irq(&logbuf_lock);
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if (len > count) {
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ret = -EINVAL;
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@ -528,7 +528,7 @@ static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence)
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if (offset)
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return -ESPIPE;
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raw_spin_lock(&logbuf_lock);
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raw_spin_lock_irq(&logbuf_lock);
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switch (whence) {
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case SEEK_SET:
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/* the first record */
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@ -552,7 +552,7 @@ static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence)
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default:
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ret = -EINVAL;
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}
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raw_spin_unlock(&logbuf_lock);
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raw_spin_unlock_irq(&logbuf_lock);
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return ret;
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}
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@ -566,14 +566,14 @@ static unsigned int devkmsg_poll(struct file *file, poll_table *wait)
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poll_wait(file, &log_wait, wait);
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raw_spin_lock(&logbuf_lock);
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raw_spin_lock_irq(&logbuf_lock);
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if (user->seq < log_next_seq) {
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/* return error when data has vanished underneath us */
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if (user->seq < log_first_seq)
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ret = POLLIN|POLLRDNORM|POLLERR|POLLPRI;
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ret = POLLIN|POLLRDNORM;
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}
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raw_spin_unlock(&logbuf_lock);
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raw_spin_unlock_irq(&logbuf_lock);
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return ret;
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}
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@ -597,10 +597,10 @@ static int devkmsg_open(struct inode *inode, struct file *file)
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mutex_init(&user->lock);
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raw_spin_lock(&logbuf_lock);
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raw_spin_lock_irq(&logbuf_lock);
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user->idx = log_first_idx;
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user->seq = log_first_seq;
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raw_spin_unlock(&logbuf_lock);
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raw_spin_unlock_irq(&logbuf_lock);
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file->private_data = user;
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return 0;
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