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authorAndi Kleen <ak@linux.intel.com>2009-12-23 15:00:20 -0500
committerAndi Kleen <ak@linux.intel.com>2009-12-23 15:00:20 -0500
commit4440095c8268c1a5e11577097d2be429cec036ca (patch)
tree7e1ca48bcd8fd0b947a7cc0edf31c0af9bbc4ec3 /kernel/rcutree_trace.c
parentf42ecb2808db5386f983d593a7c08d3ea3b94a27 (diff)
SYSCTL: Print binary sysctl warnings (nearly) only once
When printing legacy sysctls print the warning message for each of them only once. This way there is a guarantee the syslog won't be flooded for any sane program. The original attempt at this made the tables non const and stored the flag inline. Linus suggested using a separate hash table for this, this is based on a code snippet from him. The hash implies this is not exact and can sometimes not print a new sysctl due to a hash collision, but in practice this should not be a problem I used a FNV32 hash over the binary string with a 32byte bitmap. This gives relatively little collisions when all the predefined binary sysctls are hashed: size 256 bucket length number 0: [25] 1: [67] 2: [88] 3: [47] 4: [22] 5: [6] 6: [1] The worst case is a single collision of 6 hash values. Signed-off-by: Andi Kleen <ak@linux.intel.com>
Diffstat (limited to 'kernel/rcutree_trace.c')
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