The attached patch implements proper locking in ALSA lseek methods.
Note ALSA has 3 lseek implementations, but only:

	sound/core/info.c :: snd_info_entry_llseek()

requires locking.  I wrapped the function in the BKL.  According to
Jaroslav Kysela the gus_mem_proc method is only called from above.  The
third lseek, in hwdep.c, clearly doesn't need locking.  Without this
patch, the above lseek is not safe.

	Robert Love