Core: fixed a race resulting in extra sem_post()'s. The mtx->wait counter was not decremented if we were able to obtain the lock right after incrementing it. This resulted in unneeded sem_post() calls, eventually leading to EOVERFLOW errors being logged, "sem_post() failed while wake shmtx (75: Value too large for defined data type)". To close the race, mtx->wait is now decremented if we obtain the lock right after incrementing it in ngx_shmtx_lock(). The result can become -1 if a concurrent ngx_shmtx_unlock() decrements mtx->wait before the added code does. However, that only leads to one extra iteration in the next call of ngx_shmtx_lock().

/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#ifndef _NGX_LINUX_H_INCLUDED_
#define _NGX_LINUX_H_INCLUDED_


ngx_chain_t *ngx_linux_sendfile_chain(ngx_connection_t *c, ngx_chain_t *in,
    off_t limit);

extern int ngx_linux_rtsig_max;


#endif /* _NGX_LINUX_H_INCLUDED_ */