| commit | 61117bfa1b08ca048e6512c0652c568300fedf6a | |
| author | Siddhesh Poyarekar <siddhesh@sourceware.org> | |
| Fri, 5 Feb 2021 07:48:58 +0000 (5 13:18 +0530) | ||
| committer | Siddhesh Poyarekar <siddhesh@sourceware.org> | |
| Wed, 10 Feb 2021 13:38:33 +0000 (10 19:08 +0530) | ||
| tree | d752f7a8eec0c3a174c42f73f1e7927616d6d073 | treesnapshot (tar.gz zip) |
| parent | e604a5e4bb61267c58e6b6179209efe74ab5f675 | commitdiff |
tunables: Simplify TUNABLE_SET interface
The TUNABLE_SET interface took a primitive C type argument, which
resulted in inconsistent type conversions internally due to incorrect
dereferencing of types, especialy on 32-bit architectures. This
change simplifies the TUNABLE setting logic along with the interfaces.
Now all numeric tunable values are stored as signed numbers in
tunable_num_t, which is intmax_t. All calls to set tunables cast the
input value to its primitive type and then to tunable_num_t for
storage. This relies on gcc-specific (although I suspect other
compilers woul also do the same) unsigned to signed integer conversion
semantics, i.e. the bit pattern is conserved. The reverse conversion
is guaranteed by the standard.
The TUNABLE_SET interface took a primitive C type argument, which
resulted in inconsistent type conversions internally due to incorrect
dereferencing of types, especialy on 32-bit architectures. This
change simplifies the TUNABLE setting logic along with the interfaces.
Now all numeric tunable values are stored as signed numbers in
tunable_num_t, which is intmax_t. All calls to set tunables cast the
input value to its primitive type and then to tunable_num_t for
storage. This relies on gcc-specific (although I suspect other
compilers woul also do the same) unsigned to signed integer conversion
semantics, i.e. the bit pattern is conserved. The reverse conversion
is guaranteed by the standard.