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cxl: Fix afu_read() not doing finish_wait() on signal or non-blocking

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If afu_read() returned due to a signal or the AFU file descriptor being
opened non-blocking it would not call finish_wait() before returning,
which could lead to a crash later when something else wakes up the wait
queue.

This patch restructures the wait logic to ensure that the cleanup is
done correctly.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Ian Munsie 2014-10-09 11:17:46 +11:00 committed by Michael Ellerman
parent a9282d01cf
commit d53ba6b3bb
1 changed files with 16 additions and 6 deletions
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22
drivers/misc/cxl/file.c
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@ -273,6 +273,7 @@ static ssize_t afu_read(struct file *file, char __user *buf, size_t count,
struct cxl_context *ctx = file->private_data;
struct cxl_event event;
unsigned long flags;
int rc;
DEFINE_WAIT(wait);
if (count < CXL_READ_MIN_SIZE)
@ -285,13 +286,17 @@ static ssize_t afu_read(struct file *file, char __user *buf, size_t count,
if (ctx_event_pending(ctx))
break;
if (file->f_flags & O_NONBLOCK) {
rc = -EAGAIN;
goto out;
}
if (signal_pending(current)) {
rc = -ERESTARTSYS;
goto out;
}
spin_unlock_irqrestore(&ctx->lock, flags);
if (file->f_flags & O_NONBLOCK)
return -EAGAIN;
if (signal_pending(current))
return -ERESTARTSYS;
pr_devel("afu_read going to sleep...\n");
schedule();
pr_devel("afu_read woken up\n");
@ -336,6 +341,11 @@ static ssize_t afu_read(struct file *file, char __user *buf, size_t count,
if (copy_to_user(buf, &event, event.header.size))
return -EFAULT;
return event.header.size;
out:
finish_wait(&ctx->wq, &wait);
spin_unlock_irqrestore(&ctx->lock, flags);
return rc;
}
static const struct file_operations afu_fops = {