At Tue, 3 Dec 2002 04:55:15 +0100, Duncan Sands wrote: > > On Tuesday 03 December 2002 13:01, Takashi Iwai wrote: > > At Tue, 3 Dec 2002 04:07:52 +0100, > > > > Duncan Sands wrote: > > > Got this with today 2.5 BK tree: > > > > > > Debug: sleeping function called from illegal context at > > > include/asm/semaphore.h:119 Call Trace: > > > [<c0113f1a>] __might_sleep+0x52/0x58 > > > [<c024291a>] snd_cs46xx_iec958_put+0x36/0xf8 > > > [<c0217f28>] snd_ctl_elem_write+0xe0/0x1a4 > > > [<c0218360>] snd_ctl_ioctl+0x184/0x2c8 > > > [<c01462e6>] sys_ioctl+0x1fa/0x244 > > > [<c01088f7>] syscall_call+0x7/0xb > > > > ouch, we are using rwlock in the control ioctls. > > > > mutex is necessary for many controls, so we cannot suppress the use of > > mutex in control callbacks. > > but temporary unlocking looks ad-hoc, too... > > If I understand right, the problem is that snd_ctl_elem_write > acquires control_rwlock, which is a rw spinlock. It then calls > snd_cs46xx_iec958_put which acquires chip->spos_mutex, > which is a semaphore. Thus the message. Now I deduce > from the fact that you don't use read_lock_irqsave that the > data structure is not read from interrupt context. That means > you are only protecting against other CPUs. So why not use > a semaphore instead of a spinlock?
hmm, there are some places calling with irq lock. for example, snd_ctl_notify() can be called from the interrupt handler for some interrupts like h/w volume change. however, it seems that a single rwlock is used for the management of two different lists. and snd_ctl_elem_write() uses card->controls only, whereas snd_ctl_notify() uses card->ctl_files only. hence, we can merge two locks, rwsem for card->controls and rwlock for card->ctl_files. i'll give a try. ciao, Takashi ------------------------------------------------------- This SF.net email is sponsored by: Get the new Palm Tungsten T handheld. Power & Color in a compact size! http://ads.sourceforge.net/cgi-bin/redirect.pl?palm0002en _______________________________________________ Alsa-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/alsa-devel
