From: Roland Dreier <rdreier@cisco.com>
To: Andrew Morton <akpm@osdl.org>
Cc: arjan@infradead.org, mingo@elte.hu, zach.brown@oracle.com,
openib-general@openib.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Convert idr's internal locking to _irqsave variant
Date: Thu, 13 Jul 2006 18:08:17 -0700 [thread overview]
Message-ID: <adazmfdq9ha.fsf@cisco.com> (raw)
In-Reply-To: 20060713144341.97d4f771.akpm@osdl.org
> Good point, a try-again loop would work. Do we really need the caller to
> maintain a cache? I suspect something like
>
> drat:
> if (idr_pre_get(GFP_KERNEL) == ENOMEM)
> give_up();
> spin_lock();
> ret = idr_get_new();
> spin_unlock();
> if (ret == ENOMEM)
> goto drat;
>
> would do it.
The problem (for my tiny brain at least) is that I don't know where
idr_pre_get() can put the memory it allocates if there's no lock in
the idr structure -- how do you maintain internal consistency if no
locks are held when filling the cache?
Having the caller hold a chunk of memory in a stack variable was the
trick I came up with to get around that.
- R.
next prev parent reply other threads:[~2006-07-14 1:11 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-11 20:10 ipoib lockdep warning Zach Brown
2006-07-11 21:16 ` Michael S. Tsirkin
2006-07-11 21:40 ` Sean Hefty
2006-07-11 21:50 ` [openib-general] " Zach Brown
2006-07-11 22:54 ` Roland Dreier
2006-07-11 23:27 ` Zach Brown
2006-07-11 23:43 ` Roland Dreier
2006-07-11 23:53 ` Zach Brown
2006-07-12 0:06 ` Roland Dreier
2006-07-12 9:38 ` Ingo Molnar
2006-07-12 11:09 ` Michael S. Tsirkin
2006-07-12 16:31 ` [openib-general] " Sean Hefty
2006-07-12 18:56 ` Roland Dreier
2006-07-13 15:55 ` [PATCH] IB/core: use correct gfp_mask in sa_query Michael S. Tsirkin
2006-07-12 19:06 ` [openib-general] ipoib lockdep warning Roland Dreier
2006-07-12 20:45 ` [PATCH] Convert idr's internal locking to _irqsave variant Roland Dreier
2006-07-12 21:14 ` Ingo Molnar
2006-07-13 1:30 ` Andrew Morton
2006-07-13 15:42 ` Roland Dreier
2006-07-13 20:54 ` Andrew Morton
2006-07-13 21:03 ` Roland Dreier
2006-07-13 21:05 ` Arjan van de Ven
2006-07-14 0:18 ` Roland Dreier
2006-07-14 6:20 ` Arjan van de Ven
2006-07-13 21:43 ` Andrew Morton
2006-07-14 1:08 ` Roland Dreier [this message]
2006-07-14 1:18 ` Andrew Morton
2006-07-14 1:30 ` Andrew Morton
2006-07-17 15:57 ` Roland Dreier
2006-07-12 2:33 ` [openib-general] ipoib lockdep warning Roland Dreier
2006-07-12 6:49 ` Arjan van de Ven
2006-07-12 19:01 ` Roland Dreier
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