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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: Kazunori Asayama <asayama@sm.sony.co.jp>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Kazunori Asayama 2007-06-29 10:58:08 +10:00 committed by Paul Mackerras
parent fe2f896d67
commit 933b0e3524
1 changed files with 5 additions and 4 deletions
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9
arch/powerpc/platforms/cell/spufs/file.c
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@ -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;