Rather than having a piece of paper recording which errno values have been used for what, the author thought why not place then in one table in the driver code. As a guesstimate, over half the code in this driver is dedicated to sanity checking and reporting errors. Those errors may come from the host machine, the SCSI HBA or its associated hardware, or the transport or the storage device. For near end errors some creative license is taken with errno values (e.g. ENOTSOCK) to convey a better sense of what this driver is objecting to. Signed-off-by: Douglas Gilbert <dgilbert@xxxxxxxxxxxx> --- drivers/scsi/sg.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index d048c1f371ce..4fee90cca852 100644 --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -389,6 +389,48 @@ static void sg_rep_rq_state_fail(struct sg_device *sdp, #define SG_LOG(depth, sdp, fmt, a...) #endif /* end of CONFIG_SCSI_LOGGING && SG_DEBUG conditional */ +/* + * Unless otherwise noted, functions that return int will return 0 for + * good/successful or a negated errno value. Here is list of errno_s generated + * by this driver: + * + * E2BIG sum(dlen) > tot_fd_thresh ; slave dxfer_len > master dxfer_len + * EACCES user (process) does not have sufficient privilege or capabilities + * EADDRINUSE sharing: slave file descriptor already in share + * EADDRNOTAVAIL sharing: master file descriptor already in share + * slave request but no preceding master request + * EAGAIN [aka EWOULDBLOCK]; occurs when O_NONBLOCK set on open() or + * SGV4_FLAG_IMMED given, and SG_IORECEIVE (or read(2)) not ready + * EBUSY 'Device or resource busy'; this uses open(O_NONBLOCK) but another + * has open(O_EXCL); reserve request in use (e.g. when mmap() called) + * EDOM numerical error, command queueing false and second command + * attempted when one already outstanding + * EFAULT problem moving data to or from user space + * EIDRM block request unexpectedly missing + * EINTR interrupted system call (generated by kernel, not this driver) + * EINVAL flags or other input information contradicts or disallowed + * EIO only kept for backward compatibility, too generic to be useful + * ELOOP sharing: file descriptor can't share with itself + * EMSGSIZE cdb too long (> 252 bytes) or too short (less than 6 bytes) + * ENODATA sharing: no data xfer requested; mmap or direct io problem + * SG_IOABORT: no match on pack_id or tag; mrq: no active reqs + * ENODEV target (SCSI) device associated with the fd has "disappeared" + * ENOMEM obvious; could be some pre-allocated cache that is full + * ENOMSG data transfer setup needed or (direction) disallowed (sharing) + * ENOSTR slave request abandoned due to master error or state + * ENOTSOCK sharing: file descriptor for sharing unassociated with sg driver + * ENXIO 'no such device or address' SCSI mid-level processing errors + * (e.g. command timeouts); also sg info not in 'file' struct + * EPERM not permitted (even if has ACCES); v1+2,v3,v4 interface usage + * violation, opened read-only but SCSI command not listed read-only + * EPROTO logic error (in driver); like "shouldn't get here" + * EPROTOTYPE atomic state change failed unexpectedly + * ERANGE multiple requests: usually bad flag values + * ERESTARTSYS should not be seen in user space, associated with an + * interruptable wait; will restart system call or give EINTR + * EWOULDBLOCK [aka EAGAIN]; additionally if the 'more async' flag is set + * SG_IOSUBMIT may yield this error + */ /* * The SCSI interfaces that use read() and write() as an asynchronous variant of -- 2.17.1
