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* Change get_next_sem_info() to be index based, not ID based - the semaphore IDs

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aren't monotonically increasing which this code was assuming. This fixes bug
  #4917.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@34074 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Axel Dörfler 2009-11-16 13:08:36 +00:00
parent 9b716314fc
commit 07d4556346
1 changed files with 13 additions and 21 deletions
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34
src/system/kernel/sem.cpp
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@ -1123,47 +1123,39 @@ _get_next_sem_info(team_id teamID, int32 *_cookie, struct sem_info *info,
if (team == NULL)
return B_BAD_TEAM_ID;
int32 id = *_cookie;
sem_entry* sem = NULL;
if (id != 0) {
// shortcut to the first entry
sem = &sSems[id % sMaxSems];
GRAB_SEM_LOCK(*sem);
// Check if the semaphore got deleted or reused in the mean time
if (sem->id != id)
sem = NULL;
RELEASE_SEM_LOCK(*sem);
}
if (sem == NULL)
sem = (sem_entry*)list_get_first_item(&team->sem_list);
// TODO: find a way to iterate the list that is more reliable
sem_entry* sem = (sem_entry*)list_get_first_item(&team->sem_list);
int32 newIndex = *_cookie;
int32 index = 0;
bool found = false;
while (!found) {
// find the next entry to be returned
while (sem != NULL && id >= sem->id)
while (sem != NULL && index < newIndex) {
sem = (sem_entry*)list_get_next_item(&team->sem_list, sem);
index++;
}
if (sem == NULL)
return B_BAD_VALUE;
GRAB_SEM_LOCK(*sem);
if (sem->id != -1 && sem->u.used.owner == team) {
// found one!
fill_sem_info(sem, info, size);
id = sem->id;
newIndex = index + 1;
found = true;
}
} else
newIndex++;
RELEASE_SEM_LOCK(*sem);
}
if (!found)
return B_BAD_VALUE;
*_cookie = id;
*_cookie = newIndex;
return B_OK;
}