Hi, Gene Heskett wrote: > Perhaps that patch could be reverted,
It had its legitimate intentions, 10 years ago. See https://github.com/torvalds/linux/commit/210ba1d1724f5c4ed87a2ab1a21ca861a915f734 and a glimpse of the following woes http://lkml.iu.edu/hypermail//linux/kernel/0807.0/0287.html (The culprits already suffered duely. Hehehe.) The decisive change is not easy to spot. It's the loss of the function static int test_unit_ready(Scsi_CD *cd) with the line return sr_do_ioctl(cd, &cgc); sr_do_ioctl() has a waiting loop that eats "still undecided" replies and retries at most 10 times. It still exists in the current kernel https://github.com/torvalds/linux/blob/master/drivers/scsi/sr_ioctl.c where in line 223 ff. we can see the old timeout of 20 seconds if (!cgc->quiet) sr_printk(KERN_INFO, cd, "CDROM not ready yet.\n"); if (retries++ < 10) { /* sleep 2 sec and try again */ ssleep(2); goto retry; } else { /* 20 secs are enough? */ err = -ENOMEDIUM; break; } The replacement for test_unit_ready() is a call to scsi_test_unit_ready() which does not call a function with retry loop. For the purpose of sr_drive_status(), the loop is really inappropriate. This function shall obtain the drive status and not wait until the status of the medium is decided. Regrettably the subsequent correction attempts never reached the doings of drivers/cdrom/cdrom.c function open_for_data(). By the original change it lost its loop and never got a new one. My fix proposal is to create a function with such a loop and to let open_for_data() use it instead of the call of cdo->drive_status(), which actually is sr_drive_status(). Currently this call is in line 1068 of https://github.com/torvalds/linux/blob/master/drivers/cdrom/cdrom.c > and the timeout made say 2 minutes, > by which time the drive should be able to make up its mind 30 seconds seems to be enough for all normal situations. My longest experiment result with various drives and media was 18 seconds. One would have to convince the hypothetical committer why 120 is needed. But before commit comes the test and before test comes the recent kernel on real iron. I only have code for now and feel fewly talented for the missing steps. > That I think we can all agree is a PITA. Oh. I know some more such dumplings. Have a nice day :) Thomas
