Messages in this thread | | | Date | Wed, 9 Feb 2011 15:42:31 -0800 | From | Dmitry Torokhov <> | Subject | Re: [PATCH 1/2] misc: add CARMA DATA-FPGA Access Driver |
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On Wed, Feb 09, 2011 at 03:35:45PM -0800, Ira W. Snyder wrote: > On Wed, Feb 09, 2011 at 10:27:40AM -0800, Dmitry Torokhov wrote: > > [ snip stuff I've already fixed in the next version ] > > > > > > > The requirement is that the device stay open during reconfiguration. > > > This provides for that. Readers just block for as long as the device is > > > not producing data. > > > > OK, you still need to make sure you do not touch free/used buffer while > > device is disabled. Also, you need to kick readers if you unbind the > > driver, so maybe a new flag priv->exists should be introduced and > > checked. > > > > I don't understand what you mean by "kick readers if you unbind the > driver". The kernel automatically increases the refcount on a module > when a process is using the module. This shows up in the "Used by" > column of lsmod's output. > > The kernel will not let you rmmod a module with a non-zero refcount. You > cannot get into the situation where you have rmmod'ed the module and a > reader is still blocking in read()/poll().
However you can still unbind the driver from the device by writing into driver's sysfs 'unbind' attribute.
See drivers/base/bus.c::driver_unbind().
Thanks.
-- Dmitry
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