Hi Andreas, (please turn off HTML mail.) Andreas Huber wrote: > There is a reference count bug in the driver code. The driver's > active_ref count may become negative which leads to unpredictable > behavior. (mpeg video device inaccessible, etc ...) Hmm, the patchset didn't touch active_ref handling. active_ref was added by v2.6.25-rc3~132^2~7 (V4L/DVB (7194): cx88-mpeg: Allow concurrent access to cx88-mpeg devices, 2008-02-11) and relies on three assumptions: * (successful) calls to cx8802_driver::request_acquire are balanced with calls to cx8802_driver::request_release; * cx8802_driver::advise_acquire is non-null if and only if cx8802_driver::advise_release is (since both are NULL for blackbird, non-NULL for dvb); * no data races. I suppose it would be more idiomatic to use an atomic_t, but access to active_ref was previously protected by the BKL and now it is protected by core->lock. So it's not clear to me why this doesn't work. Any hints? (e.g., a detailed reproduction recipe, or a log after adding a printk to find out when exactly active_ref becomes negative) Thanks for reporting. Jonathan -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
