Em Wed, 10 Jun 2015 18:27:30 +0100 Andy Furniss <adf.lists@xxxxxxxxx> escreveu: > Mauro Carvalho Chehab wrote: > > > Just applied a fix for it: > > http://git.linuxtv.org/cgit.cgi/v4l-utils.git/commit/?id=c7c9af17163f282a147ea76f1a3c0e9a0a86e7fa > > > > It will retry up to 10 times. This should very likely be enough if the > > driver doesn't have any bug. > > > > Please let me know if this fixes the issue. > > No, it doesn't, so I reverted the above and added back my hack + a > counter as below and it seems to be retrying > a million times. Hmm.... that's likely a bug at the demod driver. It doesn't make much sense to keep a mutex hold for that long. Anyway, I modified the patch to use a timeout of 1 second, instead of trying 10 times. It is still a hack, as IMHO this is a driver bug, but it should produce a better result. Please check if the patch below works for you. You may change the MAX_TIME there if 1 second is not enough. It could be interesting if you add a printf with the difference between start and end time, for us to have an idea about how much time the driver is kept on such unreliable state. Thanks! Mauro [PATCH] libdvbv5: use a timeout for ioctl Some frontends don't play nice: they return -EAGAIN if the device doesn't lock. That actually means that it may take some time for some ioctl's to succeed. On experimental tests, the loop may happen ~2 million times! Well, better to waste power on a loop than to fail. So, let's change the code that detects EAGAIN by a loop that waits up to 1 second. This is not the right thing to do, but the Kernel drivers require fixes. We can do it only for newer versions of the Kernel. Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxx> diff --git a/lib/libdvbv5/dvb-demux.c b/lib/libdvbv5/dvb-demux.c index 867d7b9dddde..af124ae3a7cc 100644 --- a/lib/libdvbv5/dvb-demux.c +++ b/lib/libdvbv5/dvb-demux.c @@ -30,6 +30,7 @@ #include <string.h> #include <unistd.h> #include <stdio.h> +#include <time.h> #include <errno.h> #include <sys/ioctl.h> @@ -40,12 +41,25 @@ #include <libdvbv5/dvb-demux.h> +#define MAX_TIME 10 /* 1.0 seconds */ + #define xioctl(fh, request, arg...) ({ \ - int __rc, __retry; \ + int __rc; \ + struct timespec __start, __end; \ \ - for (__retry = 0; __retry < 10; __retry++) { \ + clock_gettime(CLOCK_MONOTONIC, &__start); \ + do { \ __rc = ioctl(fh, request, ##arg); \ - } while (__rc == -1 && ((errno == EINTR) || (errno == EAGAIN)));\ + if (__rc != -1) \ + break; \ + if (!((errno == EINTR) | (errno == EAGAIN))) \ + break; \ + clock_gettime(CLOCK_MONOTONIC, &__end); \ + if (__end.tv_sec * 10 + __end.tv_nsec / 100000000 > \ + __start.tv_sec * 10 + __start.tv_nsec / 100000000 + \ + MAX_TIME) \ + break; \ + } while (1); \ \ __rc; \ }) diff --git a/lib/libdvbv5/dvb-fe.c b/lib/libdvbv5/dvb-fe.c index 48b09cd9ceaa..8607401841f2 100644 --- a/lib/libdvbv5/dvb-fe.c +++ b/lib/libdvbv5/dvb-fe.c @@ -26,6 +26,7 @@ #include <inttypes.h> #include <math.h> #include <stddef.h> +#include <time.h> #include <unistd.h> #include <config.h> @@ -43,12 +44,25 @@ static int libdvbv5_initialized = 0; # define N_(string) string +#define MAX_TIME 10 /* 1.0 seconds */ + #define xioctl(fh, request, arg...) ({ \ - int __rc, __retry; \ + int __rc; \ + struct timespec __start, __end; \ \ - for (__retry = 0; __retry < 10; __retry++) { \ + clock_gettime(CLOCK_MONOTONIC, &__start); \ + do { \ __rc = ioctl(fh, request, ##arg); \ - } while (__rc == -1 && ((errno == EINTR) || (errno == EAGAIN)));\ + if (__rc != -1) \ + break; \ + if (!((errno == EINTR) | (errno == EAGAIN))) \ + break; \ + clock_gettime(CLOCK_MONOTONIC, &__end); \ + if (__end.tv_sec * 10 + __end.tv_nsec / 100000000 > \ + __start.tv_sec * 10 + __start.tv_nsec / 100000000 + \ + MAX_TIME) \ + break; \ + } while (1); \ \ __rc; \ }) -- 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
