Messages in this thread | | | Subject | Re: [apparmor] [PATCH v2] APPARMOR: add sid to profile mapping and sidrecycling | From | "Seth Arnold" <> | Date | Tue, 30 Nov 2010 10:12:20 +0000 |
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Please forgive the rubbish blackberry quoting.
+ +/* find the first zero bit in the sid_bitmap array */ +spin_lock(&aa_sid_hash_table->lock); +for (i = 0; i < AA_SID_BITMAP_SIZE; i++) { +for (j = 0; j < 32; j++) { +if (!(sid_bitmap[i] & (1 << j))) { +/* convert offset to sid */ +sid = i * 32 + j; +goto alloc_ok; +} +} +} +spin_unlock(&aa_sid_hash_table->lock);
This could be 32768 bit comparisons performed under spinlock (unlikely, perhaps, but that is the size of the datastructures...). At the least a check for sid_bitmap[I]!=0xFFFFFFFF should be placed in the outer for loop, but that could still leave 1024 word comparisons under spinlock, which feels expensive to me.
Thanks
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