Hi Romain, Em Mon, 26 May 2014 16:17:48 +0200 (CEST) Romain Baeriswyl <Romain.Baeriswyl@xxxxxxxxxx> escreveu: > Dear Mauro, > > We are using the Linux DVB frontend module on our platform and > we are facing an issue when having concurrent calls with FE_SET_FRONTEND > and FE_GET_FRONTEND ioctl. > > Issue is that both ioctls are using the same dtv_property_cache buffer. > If a FE_SET_FRONTEND ioctl is interrupted by a FE_GET_FRONTEND then the > dtv_property_cache is overwritten with the result of the FE_GET_FRONTEND. > When the FE_SET_FRONTEND operation resumes, the dtv_property_cache may > not be accurate anymore. > > Did you already face this issue? No. Never tried to do it in practice, but I don't think it is even possible to have two concurrent ioctl calls ATM, because there is a semaphore at dvb_frontend_ioctl() preventing it. > Up to now I tried, without success, to think on a fix that does not impact > too much the existing code. > > One solution could be to have one cache for reading properties and one other > cache for writing properties, but this will impact all the drivers below > the DVB frontend. > > Do you see another less impacting solution? Are you sure that the corruption you're seeing is not at userspace sharing the same buffer for both ioctl's? > > Best regards, > > Romain Baeriswyl > > Abilis Systems > 3, chemin Pré Fleuri > CH-1228 Plan-Les-Ouates > Geneva > > > > > -- > 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 -- 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
