Messages in this thread | | | Date | Fri, 19 Aug 2011 09:32:09 +0100 | From | Martyn Welch <> | Subject | Re: [PATCH 3/5] staging: vme: add functions for bridge module refcounting |
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On 13/08/11 09:54, Emilio G. Cota wrote: > On Fri, Aug 12, 2011 at 12:30:49 +0200, Manohar Vanga wrote: >> This patch adds functions that allow for reference counting >> bridge modules. The patch introduces the functions >> 'vme_bridge_get()' and 'vme_bridge_put()'. > (snip) >> +int vme_bridge_get(unsigned int bus_id) > (snip) >> +void vme_bridge_put(struct vme_bridge *bridge) > > Note the input parameter imbalance; in fact this is serious > (see my email on patch 5) because _get() needs to acquire > vme_buses_lock, whereas _put() doesn't. Since a caller with > bridge has bridge->num, but the opposite doesn't hold (num > doesn't give you the bridge without acquiring vme_buses_lock), > it seems reasonable to me to take the bus_id as the input for > both functions, because the requirements on the caller are lower. >
Patch 4 makes changes the struct vme_bridge to struct vme_dev. Looking at the callers we are then effectively doing:
vme_bridge_get(vme_dev.id)
Then in vme_bridge_get(), looping through all the buses to find the one with the correct id...
We could just pass in the struct vme_dev to both functions.
Martyn
> But the locking needs to be handled with care, see my reply > to patch 5. > > Emilio > > _______________________________________________ > devel mailing list > devel@linuxdriverproject.org > http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
-- Martyn Welch (Principal Software Engineer) | Registered in England and GE Intelligent Platforms | Wales (3828642) at 100 T +44(0)127322748 | Barbirolli Square, Manchester, E martyn.welch@ge.com | M2 3AB VAT:GB 927559189
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