Messages in this thread |  | | | Date | Sat, 4 Jul 2009 12:33:48 -0400 (EDT) | | From | "Robert P. J. Day" <> | | Subject | weekly column and a question about module_init() error codes |
in a spate of self-promotion that probably has little interest for members of *this* list, i'm now writing a weekly column for linux.com for kernel newbies, first two pieces here:
http://cli.gs/8WMgM9 http://cli.gs/Zd2MuG
yes, i know it's trivial stuff but look at it this way -- if i can explain it properly, then they won't be bugging *you* with those questions. :-)
and regarding return codes from module_init() routines, i realize that you need to return zero to represent success so that the module is loaded but, if anything goes wrong, you should return a negative value corresponding to some value out of include/asm-generic/errno-base.h:
#define EPERM 1 /* Operation not permitted */ #define ENOENT 2 /* No such file or directory */ #define ESRCH 3 /* No such process */ #define EINTR 4 /* Interrupted system call */ #define EIO 5 /* I/O error */ ... snip ... however, based on some tests i ran, regardless of what error code i return, a manual "insmod" always returns a shell error code ($?) of 1. the message *printed* will correspond to the actual error value returned, such as returning -EIO printing:
# insmod hi.ko insmod: error inserting 'hi.ko': -1 Input/output error #
i'm assuming that, if i'm running insmod as part of a script and can check only the return code, all i'm going to get is 0 or 1 (success or fail), and there's no way to extract the actual value. (i could capture the error string printed, but that's a bit of a pain -- getting the numeric value would be so much easier.)
or am i missing something painfully obvious? thanks.
rday --
======================================================================== Robert P. J. Day Waterloo, Ontario, CANADA Linux Consulting, Training and Annoying Kernel Pedantry.
Web page: http://crashcourse.ca Linked In: http://www.linkedin.com/in/rpjday Twitter: http://twitter.com/rpjday ======================================================================== -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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