----- Original Message -----
> From: [email protected]
> To: "Jan Stancek" <[email protected]>
> Cc: [email protected]
> Sent: Monday, 24 June, 2013 3:54:47 PM
> Subject: Re: [LTP] [PATCH v2] new testcase: kmsg01
> 
> Hi!
> > > > +static void test_seek(void)
> > > > +{
> > > > +       int k, j = NUM_READ_RETRY, fd;
> > > > +       char msg[MAX_MSGSIZE];
> > > > +       unsigned long seqno[2];
> > > > +
> > > > +       /* 1. read() after SEEK_SET 0 returns same (first) message */
> > > > +       tst_resm(TINFO, "TEST: seek SEEK_SET 0");
> > > > +
> > > > +       fd = open("/dev/kmsg", O_RDONLY | O_NONBLOCK);
> > > > +       if (fd < 0)
> > > > +               tst_brkm(TBROK|TERRNO, cleanup, "failed to open 
> > > > /dev/kmsg");
> > > > +
> > > > +       while (j) {
> > > > +               for (k = 0; k < 2; k++) {
> > > > +                       TEST(read(fd, msg, sizeof(msg)));
> > > > +                       if (TEST_RETURN == -1) {
> > > > +                               if (errno == EPIPE)
> > > > +                                       break;
> > > > +                               else
> > > > +                                       tst_brkm(TBROK|TTERRNO, cleanup,
> > > > +                                               "failed to read 
> > > > /dev/kmsg");
> > > > +                       }
> > > > +                       if (get_msg_fields(msg, NULL, &seqno[k]) != 0)
> > > > +                               tst_resm(TFAIL, "failed to parse seqid: 
> > > > %s",
> > > > +                                       msg);
> > > > +                       if (k == 0)
> > > > +                               if (lseek(fd, 0, SEEK_SET) == -1)
> > > > +                                       tst_resm(TFAIL|TERRNO,
> > > > +                                               "SEEK_SET 0 failed");
> > > > +               }
> > > > +
> > > > +               if (TEST_RETURN != -1)
> > > > +                       break;
> > > > +
> > > > +               /* give a second to whoever overwrote first message to 
> > > > finish */
> > > > +               sleep(1);
> > > > +               j--;
> > > > +
> > > > +               /* read returned EPIPE, reopen fd and try again */
> > > > +               SAFE_CLOSE(cleanup, fd);
> > > > +               fd = open("/dev/kmsg", O_RDONLY | O_NONBLOCK);
> > > > +               if (fd < 0)
> > > > +                       tst_brkm(TBROK|TERRNO, cleanup,
> > > > +                               "failed to open /dev/kmsg");
> > > 
> > > I guess that the comment says something different than the code, there
> > > is no read involved here.
> > 
> > Read mentioned here is the one at the beginning of for loop. This line can
> > only
> > be reached if that read returned EPIPE. Other failures will end with TBROK.
> > If read succeeded this line is never reached, "if (TEST_RETURN != -1)"
> > above
> > will break the while loop.
> 
> Ah it could be read as imperative sentence too, which confused me
> slightly.
> 
> I guess that "read has returned EPIPE" would be clearer...

Pushed with changes to SAFE_CLOSE in child process and to the comment above,
with yours and Mike's ACK.

Regards,
Jan

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