Messages in this thread | | | Date | Fri, 11 Mar 2005 12:04:49 -0500 | From | Jody McIntyre <> | Subject | Re: [PATCH, RFC 1/3] Add sem_getcount() to arches that lack it |
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On Fri, Mar 11, 2005 at 12:27:47PM +0000, Matthew Wilcox wrote:
> > But I guess it's a bit hard to justify adding more infrastructure to > > support a single callsite which has a simple alternative. So if you could > > please add the separate counter? > > It's pretty *small* infrastructure, and it gives me something to whine at > people about when they use atomic_read on something that isn't an atomic.
Agreed, but I don't mind adding a separate counter. However...
> If we are going to get rid of sem_getcount, could we rename the 'count' > variables, at least on i386 and ppc to make it clear that you're not > supposed to do this ... maybe to 'count_$ARCH'?
I'm working on a patch to do just that. It fails when building XFS:
fs/xfs/xfs_inode_item.c: In function `xfs_inode_item_pushbuf': fs/xfs/xfs_inode_item.c:803: error: structure has no member named `count' fs/xfs/xfs_inode_item.c:825: error: structure has no member named `count'
fs/xfs/linux-2.6/sema.h: #define valusema(sp) (atomic_read(&(sp)->count))
It seems getting the value of a semaphore is more common than it appears at first glance. I don't see how this code could possibly work on parisc. Therefore I propose:
1. Adding sem_getcount() everywhere, as in my original patch. 2. Renaming count to count_$ARCH as willy suggested. 3. Anyone who abuses semaphores will now break. Fix them to use sem_getcount().
I'll work on that over the weekend unless anyone has any better ideas.
Jody
> > -- > "Next the statesmen will invent cheap lies, putting the blame upon > the nation that is attacked, and every man will be glad of those > conscience-soothing falsities, and will diligently study them, and refuse > to examine any refutations of them; and thus he will by and by convince > himself that the war is just, and will thank God for the better sleep > he enjoys after this process of grotesque self-deception." -- Mark Twain
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