Messages in this thread Patch in this message | | | Subject | IS_ERR Threshold Value | From | Erik Frederiksen <> | Date | Wed, 28 Jun 2006 14:57:07 -0600 |
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from include/asm-mips/errno.h #define EDQUOT 1133 /* Quota exceeded */
I noticed that the errno value for EDQUOT on MIPS is considerably larger than all others. This can lead to a situation where functions using ERR_PTR() to return error codes in pointers cannot return this error code without IS_ERR() thinking that the pointer is valid. In my case, it caused an alignment exception in the XFS open call when quota has been exceeded in the linux-mips 2.6.14 kernel. I think that the XFS code has changed enough that this bug isn't in newer versions, though I haven't done a thorough investigation.
I've supplied a patch that addresses this situation by changing the threshold used by IS_ERR if EMAXERRNO is defined and greater than 1000. Perhaps permanently raising the threshold value to something >1133 is sufficient.
Looking forward to your feedback.
Erik Frederiksen Firmware Design Engineer Co-op PMC-Sierra Saskatoon
diff -Nau [ab]/include/linux/err.h --- a/include/linux/err.h 2005-10-30 13:14:22.000000000 -0600 +++ b/include/linux/err.h 2006-06-28 10:38:43.000000000 -0600 @@ -12,8 +12,23 @@ * * This should be a per-architecture thing, to allow different * error and pointer decisions. + * + * Updated by Erik Frederiksen (erik_frederiksen@pmc-sierra.com) + * errno values on MIPS go up to 1133 for EDQUOT. The threshold + * is adjusted so that returning large errnos in a pointer + * does not result in a valid pointer according to IS_ERR. */ -#define IS_ERR_VALUE(x) unlikely((x) > (unsigned long)-1000L) + +#define ERR_PTR_THRESHOLD 1000 +#define IS_ERR_VALUE(x) \ + unlikely((x) > (unsigned long)-(long)ERR_PTR_THRESHOLD ) +#ifdef EMAXERRNO +# if EMAXERRNO >= ERR_PTR_THRESHOLD +# undef IS_ERR_VALUE +# define IS_ERR_VALUE(x) \ + unlikely((x) >= (unsigned long)-(long)EMAXERRNO ) +# endif +#endif static inline void *ERR_PTR(long error) {
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