From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Grant Likely <grant.likely@secretlab.ca>
Cc: Baruch Siach <baruch@tkos.co.il>,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [BUG] irq_dispose_mapping after irq request failure
Date: Tue, 12 Feb 2013 11:51:13 +1100 [thread overview]
Message-ID: <1360630273.2035.2.camel@pasglop> (raw)
In-Reply-To: <20130211205255.72B513E3530@localhost>
On Mon, 2013-02-11 at 20:52 +0000, Grant Likely wrote:
> Really the irq mappings should be using reference counting. The existing
> code is naive on this count and just releases the irq on the first call
> to irq_dispose_mapping(). I've not gotten around to fixing that. Anyone
> want to take that task on?
Is this the best approach ?
The original idea was that there was no point disposing of mappings in most
cases and keeping the mapping around would provide a bit of stability of
interrupt numbers which might come in handy for debugging etc...
The few cases where disposing of a mapping might be useful is if the underlying
physical interrupts completely disappear, as in a cascaded controller gets
removed or that sort of thing, which is a very rare case... And even then...
Could you just make irq_dispose_mapping() check if the irq desc is
active and fail/WARN/BUG if it is ? I don't see the point of adding a refcount,
that feels overkill.
Cheers,
Ben.
WARNING: multiple messages have this Message-ID (diff)
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Grant Likely <grant.likely@secretlab.ca>
Cc: Michael Ellerman <michael@ellerman.id.au>,
Baruch Siach <baruch@tkos.co.il>,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [BUG] irq_dispose_mapping after irq request failure
Date: Tue, 12 Feb 2013 11:51:13 +1100 [thread overview]
Message-ID: <1360630273.2035.2.camel@pasglop> (raw)
In-Reply-To: <20130211205255.72B513E3530@localhost>
On Mon, 2013-02-11 at 20:52 +0000, Grant Likely wrote:
> Really the irq mappings should be using reference counting. The existing
> code is naive on this count and just releases the irq on the first call
> to irq_dispose_mapping(). I've not gotten around to fixing that. Anyone
> want to take that task on?
Is this the best approach ?
The original idea was that there was no point disposing of mappings in most
cases and keeping the mapping around would provide a bit of stability of
interrupt numbers which might come in handy for debugging etc...
The few cases where disposing of a mapping might be useful is if the underlying
physical interrupts completely disappear, as in a cascaded controller gets
removed or that sort of thing, which is a very rare case... And even then...
Could you just make irq_dispose_mapping() check if the irq desc is
active and fail/WARN/BUG if it is ? I don't see the point of adding a refcount,
that feels overkill.
Cheers,
Ben.
next prev parent reply other threads:[~2013-02-12 0:51 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-11 5:31 [BUG] irq_dispose_mapping after irq request failure Baruch Siach
2013-02-11 6:19 ` Michael Ellerman
2013-02-11 6:19 ` Michael Ellerman
2013-02-11 6:44 ` Baruch Siach
2013-02-11 6:44 ` Baruch Siach
2013-02-11 20:52 ` Grant Likely
2013-02-11 20:52 ` Grant Likely
2013-02-12 0:51 ` Benjamin Herrenschmidt [this message]
2013-02-12 0:51 ` Benjamin Herrenschmidt
2013-02-12 6:18 ` Michael Ellerman
2013-02-12 6:18 ` Michael Ellerman
2013-02-12 8:53 ` Benjamin Herrenschmidt
2013-02-12 8:53 ` Benjamin Herrenschmidt
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1360630273.2035.2.camel@pasglop \
--to=benh@kernel.crashing.org \
--cc=baruch@tkos.co.il \
--cc=grant.likely@secretlab.ca \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.