Author: tridge Date: 2007-05-17 02:18:29 +0000 (Thu, 17 May 2007) New Revision: 22959
WebSVN: http://websvn.samba.org/cgi-bin/viewcvs.cgi?view=rev&root=samba&rev=22959 Log: cope with a rather interesting interaction between epoll() and fork(). See http://junkcode.samba.org/ftp/unpacked/junkcode/epoll_fork.c for why this is needed Modified: branches/SAMBA_4_0/source/lib/events/events_standard.c Changeset: Modified: branches/SAMBA_4_0/source/lib/events/events_standard.c =================================================================== --- branches/SAMBA_4_0/source/lib/events/events_standard.c 2007-05-17 01:17:43 UTC (rev 22958) +++ branches/SAMBA_4_0/source/lib/events/events_standard.c 2007-05-17 02:18:29 UTC (rev 22959) @@ -58,6 +58,9 @@ /* when using epoll this is the handle from epoll_create */ int epoll_fd; + + /* our pid at the time the epoll_fd was created */ + pid_t pid; }; /* use epoll if it is available */ @@ -68,7 +71,9 @@ */ static void epoll_fallback_to_select(struct std_event_context *std_ev, const char *reason) { + const char *cmd = talloc_asprintf(std_ev, "xterm -e gdb --pid %u", getpid()); DEBUG(0,("%s (%s) - falling back to select()\n", reason, strerror(errno))); + system(cmd); close(std_ev->epoll_fd); std_ev->epoll_fd = -1; talloc_set_destructor(std_ev, NULL); @@ -90,7 +95,9 @@ */ static int epoll_ctx_destructor(struct std_event_context *std_ev) { - close(std_ev->epoll_fd); + if (std_ev->epoll_fd != -1) { + close(std_ev->epoll_fd); + } std_ev->epoll_fd = -1; return 0; } @@ -101,9 +108,32 @@ static void epoll_init_ctx(struct std_event_context *std_ev) { std_ev->epoll_fd = epoll_create(64); + std_ev->pid = getpid(); talloc_set_destructor(std_ev, epoll_ctx_destructor); } +static void epoll_add_event(struct std_event_context *std_ev, struct fd_event *fde); + +/* + reopen the epoll handle when our pid changes + see http://junkcode.samba.org/ftp/unpacked/junkcode/epoll_fork.c for an + demonstration of why this is needed + */ +static void epoll_reopen(struct std_event_context *std_ev) +{ + struct fd_event *fde; + + close(std_ev->epoll_fd); + std_ev->epoll_fd = epoll_create(64); + if (std_ev->epoll_fd == -1) { + return; + } + std_ev->pid = getpid(); + for (fde=std_ev->fd_events;fde;fde=fde->next) { + epoll_add_event(std_ev, fde); + } +} + #define EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT (1<<0) #define EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR (1<<1) #define EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR (1<<2) @@ -116,6 +146,16 @@ struct epoll_event event; if (std_ev->epoll_fd == -1) return; + /* during an add event we need to check if our pid has changed + and re-open the epoll socket. Note that we don't need to do this + for other epoll changes */ + if (std_ev->pid != getpid()) { + epoll_reopen(std_ev); + /* the current event gets added in epoll_reopen(), so + we can return here */ + return; + } + fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR; /* if we don't want events yet, don't add an epoll_event */
