On Fri, Mar 23, 2018 at 04:38:50PM +0100, Marcus Wolf wrote: > I had no time to work on the code for monthes now and the memorisation > of my thoughts when I was programming that (approx. one year ago) is > quite pale. > > As far as I remember, I read something, that the fifo has an integrated > protection, so no external protection is needed. But absolutely unsure. > > If I will find some time within the next days, I'll have a look at the > code and try to recall. > > But the most important thing already took place: We started thinking > about it :-) You are right, here is what kfifo.h says: /* * Note about locking : There is no locking required until only * one reader * and one writer is using the fifo and no kfifo_reset() will be * called * kfifo_reset_out() can be safely used, until it will be only called * in the reader thread. * For multiple writer and one reader there is only a need to lock the writer. * And vice versa for only one writer and multiple reader there is only a need * to lock the reader. */ In the case of pi433 there is only one reader (pi433_tx_thread) and there is no need for a lock there. But the char device (pi433_write) might have multiple writers so we leave the mutex just in that function? -- Valentin _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
