On Fri, Oct 11, 2024 at 05:45:30PM -0700, Anjali Kulkarni wrote: > Add a new type PROC_CN_MCAST_NOTIFY to proc connector API, which allows a > thread to notify the kernel that it has exited abnormally. Thread can also > send the exit status code it wants returned in the notification with it. > Exiting thread can call this either when it wants to call pthread_exit() > with non-zero value or from signal handler. > > Add a new file cn_hash.c which implements a hash table storing the exit > codes of abnormally exiting threads, received by the system call above. > The key used for the hash table is the pid of the thread, so when the > thread actually exits, we lookup it's pid in the hash table and retrieve > the exit code sent by user. If the exit code in struct task is 0, we > then replace it with the user supplied non-zero exit code. > > cn_hash.c implements the hash table add, delete, lookup operations. > mutex_lock() and mutex_unlock() operations are used to safeguard the > integrity of the hash table while adding or deleting elements. > connector.c has the API calls, called from cn_proc.c, as well as calls > to allocate, initialize and free the hash table. > > Add a new flag in PF_* flags of task_struct - EXIT_NOTIFY. This flag is > set when user sends the exit code via PROC_CN_MCAST_NOTIFY. While > exiting, this flag is checked and the hash table add or delete calls > are only made if this flag is set. > > A refcount field hrefcnt is added in struct cn_hash_dev, to keep track > of number of threads which have added an entry in hash table. Before > freeing the struct cn_hash_dev, this value must be 0. > > Signed-off-by: Anjali Kulkarni <anjali.k.kulka...@oracle.com>
... > diff --git a/drivers/connector/cn_proc.c b/drivers/connector/cn_proc.c > index 44b19e696176..8c6e002069d9 100644 > --- a/drivers/connector/cn_proc.c > +++ b/drivers/connector/cn_proc.c ... > @@ -326,9 +328,16 @@ void proc_exit_connector(struct task_struct *task) > struct proc_event *ev; > struct task_struct *parent; > __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8); > + __u32 uexit_code; > + int err; > > - if (atomic_read(&proc_event_num_listeners) < 1) > + if (atomic_read(&proc_event_num_listeners) < 1) { > + if (likely(!(task->flags & PF_EXIT_NOTIFY))) > + return; > + > + err = cn_del_elem(task->pid); Hi Anjali, err is set but otherwise unused in this function; probably it can be removed. > return; > + } > > msg = buffer_to_cn_msg(buffer); > ev = (struct proc_event *)msg->data; ...