Date: Sun, 22 Apr 2001 13:13:28 -0700 (PDT) From: Joerg Wunsch <joerg@FreeBSD.org> To: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/sys/cam/scsi scsi_sa.c Message-ID: <200104222013.f3MKDTd16756@freefall.freebsd.org>
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joerg 2001/04/22 13:13:28 PDT Modified files: sys/cam/scsi scsi_sa.c Log: Fix the `tape drive spinning indefinately upon mt stat' problem. With the recent changes in the CAM error handling, some problems in the error handling of sa(4) have been uncovered. Basically, a number of conditions that are not actually errors have been mistreated as genuine errors. In particular: . Trying to read in variable length mode with a mismatched blocksize between the on-tape (virtual) blocks and the read(2) supplied buffer size, causing an ILI SCSI condition, have caused an attempt to retry the supposedly `errored' transfer, causing the tape to be read continuously until it eventually hit EOM. Since by default any simple mt(1) operation does an initial test read, an `mt stat' was sufficient to trigger this bug. Note that it's Justin's opinion that treating a NO SENSE as an EIO is another bug in CAM. I feel not authorized to fix cam_periph.c without another confirmation that i'm on the right track, however. . Hitting a filemark caused the read(2) syscall to return EIO, instead of returning a `short read'. Note that the current fix only solves this problem in variable length mode. Fixed length mode uses a different code path, and since i didn't grok all the intentions behind that handling, i did not touch it (IOW: it's still broken, and you get an EIO upon hitting a filemark). The solution is to keep track of those conditions inside saerror(), and upon completion to not call cam_periph_error() in that case. We need to make sure that the device gets unfrozen if needed though (in case of actual errors, cam_periph_error() does this on our behalf). Not objected by: mjacob (who currently doesn't have the time to review the patch) Revision Changes Path 1.68 +16 -3 src/sys/cam/scsi/scsi_sa.c To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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