On Dec 3 23:01, Takashi Yano wrote: > The queue is cleaned up by removing the entries having si_signo == 0 > while processing the queued signals, however, sigpacket::process() may > set si_signo in the queue to 0 of the entry already processed but not > succeed by calling sig_clear(). This patch ensures the sig_clear() > to remove the entry from the queue chain. For this purpose, the pointer > prev has been added to the sigpacket. This is to handle the following > case appropriately. > > Consider the queued signal chain of: > A->B->C->D > without pointer prev. Assume that the pointer 'q' and 'qnext' point to > C, and process() is processing C. If B is cleared in process(), A->next > should be set to to C in sigpacket::clear(). > > Then, if process() for C succeeds, C should be removed from the queue, > so A->next should be set to D. However, we cannot do that because we do > not have the pointer to A in the while loop in wait_sig(). > > With the pointer prev, we can easily access A and C in sigpacket::clear() > as well as A and D in the while loop in wait_sig() using the pointer prev > and next without pursuing the chain.
Sounds good. The concurrency problem is still open, right? Thanks, Corinna
