On 28.04.21 12:47, Marc Kleine-Budde wrote:
On 28.04.2021 12:24:32, Oliver Hartkopp wrote:
Maybe the way to trigger the sk_error_report(sk) we might return '-1'
while the error is then propagated inside errno.
I added some debug print in isotpsend:
diff --git a/isotpsend.c b/isotpsend.c
index 3ea574c..c2937fa 100644
--- a/isotpsend.c
+++ b/isotpsend.c
@@ -45,10 +45,11 @@
#include <libgen.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
+#include <errno.h>
#include <net/if.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/types.h>
@@ -252,10 +253,11 @@ int main(int argc, char **argv)
buf[buflen] = ((buflen % 0xFF) + 1) & 0xFF;
}
retval = write(s, buf, buflen);
+ printf("retval %d errno %d\n", retval, errno);
Note: in user space errno is only valid if retval is "-1"...
Ok, just returned '-1' in that case of blocking write (which runs into
the timeout) ...
diff --git a/net/can/isotp.c b/net/can/isotp.c
index 9f94ad3caee9..d5d541b4fed5 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -952,10 +952,11 @@ static int isotp_sendmsg(struct socket *sock,
struct msghdr *msg, size_t size)
}
if (wait_tx_done) {
/* wait for complete transmission of current pdu */
wait_event_interruptible(so->wait, so->tx.state ==
ISOTP_IDLE);
+ return -1;
}
return size;
}
And now got this:
$ date +%S.%N && ./isotpsend vcan0 -s 123 -d 321 -D 44 -b && date +%S.%N
22.411570468
retval -1 errno 1
write: Operation not permitted
So still nothing to see from "sk->sk_err = ECOMM;"
But when adding 'return -ECOMM' at the above section it works like this:
$ date +%S.%N && ./isotpsend vcan0 -s 123 -d 321 -D 44 -b && date +%S.%N
58.453452222
retval -1 errno 70
write: Communication error on send
This is obviously the expected behaviour for user space:
- get '-1' in the case of socket related errors
- get the details from errno
Maybe all that sk_err stuff is only relevant for listen/accept
constructions for connection oriented sockets and can be removed inside
isotp.c ...
Regards,
Oliver
if (retval < 0) {
perror("write");
return retval;
}
$ date +%S.%N && ./isotpsend vcan0 -s 123 -d 321 -D 44 -b && date +%S.%N
43.269173590
retval 44 errno 0
44.271162277
So it waits for the timeout as required by the '-b' option - but the errno
is not set :-/
I'm not sure what we have to return in the kernel...
Marc
