Messages in this thread | | | Subject | Re: [patch 1/4] Linux Kernel Markers - Architecture Independent Code | From | Rusty Russell <> | Date | Sun, 26 Aug 2007 06:49:30 +1000 |
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On Fri, 2007-08-24 at 12:26 -0400, Mathieu Desnoyers wrote: > * Rusty Russell (rusty@rustcorp.com.au) wrote: > > On Mon, 2007-08-20 at 16:27 -0400, Mathieu Desnoyers wrote: > > > +{ > > > + struct hlist_head *head; > > > + struct hlist_node *node; > > > + struct marker_entry *e; > > > + size_t len = strlen(name) + 1; > > > + u32 hash = jhash(name, len-1, 0); > > > + > > > + head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)]; > > > + hlist_for_each_entry(e, node, head, hlist) { > > > + if (!strcmp(name, e->name)) > > > + return e; > > > + } > > > + return NULL; > > > +} > > > > OK, don't understand the strlen, len, len-1 dance here? > > > > Let's say we have abc\0 for marker name as name input. > > len = 3 + 1 = 4 (including \0) > hash is done only on the 3 first chars, excluding the \0 (therefore the > len-1 there) > > Actually, it's like this only for a matter of consistency between > add_marker and remove_marker, which are quite similar, but add_marker > needs name_len to include the \0 value. It would be odd to change the > logic between the two functions to one including the \0 and the other > excluding it.
Sure, but that doesn't really explain why the code does:
size_t len = strlen(name) + 1; u32 hash = jhash(name, len-1, 0);
Rather than:
u32 hash = jhash(name, strlen(name), 0);
> Thanks for the review,
That's fine, just some light reading...
Cheers, Rusty. >
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