Hi Oliver, On Wed, Mar 01 2023, Oliver Hartkopp wrote: > I can not see problems or drops when using > > ./isotpsend vcan0 -s 123 -d 321 -D 9 -li > > as data producer where I added a counter: Really? I tried to modify my test program to also support blocking operation (without poll()) and setting CAN_ISOTP_WAIT_TX_DONE. It's available at https://github.com/wentasah/isotp-poll-test/blob/fd095b2242c49dc5d3e36faf5ac9f4f47fd002c7/isotp-poll-test.c. With it, I detect lost message in mainline Linux 6.2, but sometimes, it takes quite long time (a minute) before it happens. What happens is well visible with strace. When I run the receiver as (-b stands for blocking operation without poll()): strace ./isotp-poll-test -s 321 -d 123 -i -a -b -q and then the sender (-w means to use CAN_ISOTP_WAIT_TX_DONE): strace ./isotp-poll-test -s 123 -d 321 -o -w -b -q The output of the receiver is: read(3, "Hello122813", 99) = 11 read(3, "Hello122814", 99) = 11 read(3, "Hello122815", 99) = 11 read(3, "Hello122816", 99) = 11 read(3, "Hello122817", 99) = 11 read(3, "Hello122847", 99) = 11 write(2, "isotp-poll-test: ", 17isotp-poll-test: ) = 17 write(2, "Lost messages. Expected: #122818"..., 50Lost messages. Expected: #122818, received #122847) = 50 write(2, "\n", 1 ) = 1 exit_group(1) = ? Sender's output looks as follows: write(3, "Hello122813", 11) = 11 write(3, "Hello122814", 11) = 11 write(3, "Hello122815", 11) = 11 write(3, "Hello122816", 11) = 11 write(3, "Hello122817", 11) = 11 write(3, "Hello122818", 11) = 11 write(3, "Hello122819", 11) = 11 write(3, "Hello122820", 11) = 11 ... write(3, "Hello123116", 11) = 11 write(3, "Hello123117", 11) = 11 write(3, "Hello123118", 11) = 11 write(3, "Hello123119", 11) = -1 ECOMM (Communication error on send) write(2, "isotp-poll-test: ", 17isotp-poll-test: ) = 17 write(2, "write(sock, str, strlen(str))", 29write(sock, str, strlen(str))) = 29 write(2, ": Communication error on send\n", 30: Communication error on send ) = 30 exit_group(1) = ? So my impression is that this does not relate to poll() implementation changes. I also tried to update my poll patch to take into account the so->wait wait queue. But the result is the same as without it. I will send it in a separate mail. Best regards, -Michal
