Commit 8d44b958 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

posix-timers: Cleanup comments about timer ID tracking 



Describe the hash table properly and remove the IDR leftover comments.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20230425183313.038444551@linutronix.de
parent 7d990902

kernel/time/posix-timers.c

+8 −20
Original line number Diff line number Diff line
@@ -35,20 +35,17 @@ 
#include "timekeeping.h"

#include "posix-timers.h"



/*

 * Management arrays for POSIX timers. Timers are now kept in static hash table

 * with 512 entries.

 * Timer ids are allocated by local routine, which selects proper hash head by

 * key, constructed from current->signal address and per signal struct counter.

 * This keeps timer ids unique per process, but now they can intersect between

 * processes.

 */

static struct kmem_cache *posix_timers_cache;



/*

 * Lets keep our timers in a slab cache :-)

 * Timers are managed in a hash table for lockless lookup. The hash key is

 * constructed from current::signal and the timer ID and the timer is

 * matched against current::signal and the timer ID when walking the hash

 * bucket list.

 *

 * This allows checkpoint/restore to reconstruct the exact timer IDs for

 * a process.

 */

static struct kmem_cache *posix_timers_cache;



static DEFINE_HASHTABLE(posix_timers_hashtable, 9);

static DEFINE_SPINLOCK(hash_lock);
@@ -65,15 +62,6 @@ static const struct k_clock clock_realtime, clock_monotonic; 
#error "SIGEV_THREAD_ID must not share bit with other SIGEV values!"

#endif



/*

 * The timer ID is turned into a timer address by idr_find().

 * Verifying a valid ID consists of:

 *

 * a) checking that idr_find() returns other than -1.

 * b) checking that the timer id matches the one in the timer itself.

 * c) that the timer owner is in the callers thread group.

 */



/*

 * CLOCKs: The POSIX standard calls for a couple of clocks and allows us

 *	    to implement others.  This structure defines the various