negative module count in /proc/modules

[Brad Davidson]

Sorry, here are the relevant lines of /proc/modules

Module		Size	Used by		Not tainted
hostap_cs	47704	-1
hostap		87416	0	[hostap_cs]

Brad Davidson wrote:

> Here's a fun one. I got the modules usage count to go negative.
> Steps to recreate:
> 
> Install HostAP (I'm using the latest CVS tarball). Bind the modules to 
> your PCMCIA card in the PCMCIA-CS config file, and insert the card. 
> After the card is configured, physically eject it from the cardslot.
> 
> The following appears in the kernel debug log:
> wlan0: Interupt, but SWSUPPORT0 does not match: FFFF != 8A32 - card 
> removed?
> wlan0: prism2_interupt: ev=0xffff
> hostap_cs: CS_EVENT_CARD_REMOVAL
> ti113x: Routing card interupts to PCI
> wlan0: scheduled card reset
> hostap_cs: wlan0: resetting card
> wlan0: card already removed or not configured during shutdown
> wlan0: hfa384x_cmd - timeout - reg=0xfff
> hostap_cs: first command failed - is the card compatible?
> prism2_tx_timeout: wake up queue
> wlan0: card allready removed or not configured during shutdown
> hostap_cs: Netdevice wlan0 unregistered
> 
> If the same thing is done again, the usage count will drop to -2, and so 
> on.
> 
> If, when the usage count is -1, you insert the card, the device will be 
> usable, but the usage count will be 0. If you run modprobe -r hostap_cs 
> to remove the module, the system will hang (or possibly oops, on other 
> systems)
> 
> Everything works just dandy if I use 'cardctl eject' before removing the 
> device.
> 
> Seems to me that the module is getting unloaded twice - once when the 
> driver is called in interupt context because the card was ejected, and 
> another when the waiting tx request wakes up, and notices that the card 
> is gone. Locking problem?
> 
> This is all on a Pismo G3 with PCMCIA-CS 3.2.5, using the kernel PCMCIA 
> driver.
> 
> If I have some time I might go poke at the driver myself, but I'll warn 
> everybody that I'm only up to chapter 4 in "programing linux device 
> drivers", so I'm not expecting any particular results at all :)
> 
> -Brad
> 
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