Re: [PATCH][ATM] add reference counting to atm_dev

[chas williams]

In message <[e-mail]>,Duncan Sands writes:
>I was wondering about ioctl and proc calls.  Can the ATM layer call
>a driver's ioctl routine before opening a vcc?  If so, does it take a

yes

>reference to the module first (I didn't spot anything)?  Also, are

the original atm code used atm_dev_lock to keep the device from
disappearing during the ioctl.  atm_dev_lock was being used to protect
sections of code, like ioctl and atm device (de)registry.  the 2.5
code is getting changes that should improve matters.  atm_dev will
now have a reference count to keep a device from being unregistered
while someone holds a reference (ioctl or otherwise).

>calls to a driver's proc_read routine protected against module
>unloading races (I confess I didn't take the time to look into this,
>because my own driver does not sleep in proc_read)?

i believe proc has always been a troublesome child.  it has never
had any protection (via atm_dev_lock or otherwise).  you can sleep
in the proc function (since it would in user mode).  i have added some
locking to proc in the 2.5 that should make proc safer (but not very
elegant--perhaps elegance with come with the seq conversion).