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Commit 933b0e35 authored by Kazunori Asayama's avatar Kazunori Asayama Committed by Paul Mackerras
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[POWERPC] spufs: Fix lost events in poll/epoll on mfc 



When waiting for I/O events on mfc in an SPU context by using
poll/epoll syscalls, some of the events can be lost because of wrong
order of poll_wait and MFC status checks in the spufs_mfc_poll
function and non-atomic update of tagwait.  This fixes the
problem.

Signed-off-by: default avatarKazunori Asayama <asayama@sm.sony.co.jp>
Signed-off-by: default avatarJeremy Kerr <jk@ozlabs.org>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent fe2f896d

arch/powerpc/platforms/cell/spufs/file.c

+5 −4
Original line number Diff line number Diff line
@@ -1499,14 +1499,15 @@ static ssize_t spufs_mfc_write(struct file *file, const char __user *buffer, 
		if (status)

			ret = status;

	}

	spu_release(ctx);



	if (ret)

		goto out;

		goto out_unlock;



	ctx->tagwait |= 1 << cmd.tag;

	ret = size;



out_unlock:

	spu_release(ctx);

out:

	return ret;

}
@@ -1517,14 +1518,14 @@ static unsigned int spufs_mfc_poll(struct file *file,poll_table *wait) 
	u32 free_elements, tagstatus;

	unsigned int mask;



	poll_wait(file, &ctx->mfc_wq, wait);



	spu_acquire(ctx);

	ctx->ops->set_mfc_query(ctx, ctx->tagwait, 2);

	free_elements = ctx->ops->get_mfc_free_elements(ctx);

	tagstatus = ctx->ops->read_mfc_tagstatus(ctx);

	spu_release(ctx);



	poll_wait(file, &ctx->mfc_wq, wait);



	mask = 0;

	if (free_elements & 0xffff)

		mask |= POLLOUT | POLLWRNORM;