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Fix next_pid to not reallocate PIDs immediately

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This commit is contained in:
Kevin Lange 2015-07-02 21:39:43 -07:00
parent ce05bdbff7
commit a0c1350369
1 changed files with 23 additions and 8 deletions
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31
kernel/sys/process.c
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@ -36,6 +36,12 @@ static bitset_t pid_set;
/* Default process name string */
char * default_name = "[unnamed]";
/*
* This makes a nice 4096-byte bitmap. It also happens
* to be pid_max on 32-bit Linux, so that's kinda nice.
*/
#define MAX_PID 32768
/*
* Initialize the process tree and ready queue.
*/
@ -46,7 +52,7 @@ void initialize_process_tree(void) {
sleep_queue = list_create();
/* Start off with enough bits for 64 processes */
bitset_init(&pid_set, 64 / 8);
bitset_init(&pid_set, MAX_PID / 8);
/* First two bits are set by default */
bitset_set(&pid_set, 0);
bitset_set(&pid_set, 1);
@ -289,15 +295,24 @@ process_t * spawn_init(void) {
*
* @return A usable PID for a new process.
*/
static int _next_pid = 2;
pid_t get_next_pid(void) {
int index = bitset_ffub(&pid_set);
if (index == -1) {
int next = pid_set.size * 8;
bitset_set(&pid_set, next);
return next;
if (_next_pid > MAX_PID) {
int index = bitset_ffub(&pid_set);
/*
* Honestly, we don't have the memory to really risk reaching
* the point where we have MAX_PID processes running
* concurrently, so this assertion should be "safe enough".
*/
assert(index != -1);
bitset_set(&pid_set, index);
return index;
}
bitset_set(&pid_set, index);
return index;
int pid = _next_pid;
_next_pid++;
assert(!bitset_test(&pid_set, pid) && "Next PID already allocated?");
bitset_set(&pid_set, pid);
return pid;
}
/*