Message ID | a2381f11-cba1-b64d-f34e-72858f9169c6@nbd.name |
---|---|
State | Changes Requested |
Delegated to: | John Crispin |
Headers | show |
Hi Felix, The SIGTERM ignore issue I was experiencing before is no longer reproducible after I apply your patch. However, I'm concerned about a possible ignore of SIGTERM signal received during a ubus_complete_request() call. If ctx->stack_depth is 0, any such signal received between prev_uloop_initialization and the reset of ulopp_cancelling to false will be ignored. Is this "uloop_cancelling = false" really necessary? BTW, I think the reset of uloop_status and uloop_cancelled should be executed before uloop_setup_signals() like so: if (!recursive_calls++) { uloop_status = 0; uloop_cancelled = false; uloop_setup_signals(true); } Cheers, Alin On Fri, Feb 3, 2017 at 2:47 PM, Felix Fietkau <nbd@nbd.name> wrote: > Hi Alin, > > On 2017-02-03 09:29, Alin Năstac wrote: >> Hi Felix, >> >> SIGTERM & SIGINT signals received during ubus_complete_request() >> waiting for ubus_poll_data() to return are ignored due to >> uloop_cancelled being restored to its previous value it had before >> uloop_poll_data() was called. >> >> The reproduction scenario is this: >> 1) cancelled local variable is set to false, current value of uloop_cancelled >> 2) while ubus_poll_data() is waiting for a read event, a SIGTERM is >> received, so uloop_cancelled is set to true >> 3) after ubus_poll_data() returns, uloop_cancelled value gets >> overwritten with false and SIGTERM signal ends up being ignored in the >> uloop_run() >> >> The whole uloop_cancelled related logic in the ubus_complete_request() >> seems to be focused on getting out from the current recursion of >> uloop_run(), but from what I see uloop_run() capability to be called >> recursively is no longer used in ubus, so I wonder if it is still >> necessary. > I left in uloop_cancelled primarily to deal with cleaning up recursive > requests after Ctrl+c or SIGTERM when uloop is in use. > >> If the answer is no, the entire logic referring to uloop_cancelled and >> uloop_end() should be removed from libubus-req.c. Otherwise an >> additional uloop_cancelled_recursions bit mask would be needed that >> will allow to control uloop_run() exit condition for each individual >> recursion. > I think the main problem was the fact that uloop_cancelled was used > both for internal request termination and also for external use. > Here's a patch that should resolve this issue, please test: > > --- > diff --git a/libubus-io.c b/libubus-io.c > index 1075c65..1343bb2 100644 > --- a/libubus-io.c > +++ b/libubus-io.c > @@ -154,9 +154,10 @@ int __hidden ubus_send_msg(struct ubus_context *ctx, uint32_t seq, > return ret; > } > > -static int recv_retry(int fd, struct iovec *iov, bool wait, int *recv_fd) > +static int recv_retry(struct ubus_context *ctx, struct iovec *iov, bool wait, int *recv_fd) > { > int bytes, total = 0; > + int fd = ctx->sock.fd; > static struct { > struct cmsghdr h; > int fd; > @@ -191,7 +192,7 @@ static int recv_retry(int fd, struct iovec *iov, bool wait, int *recv_fd) > > if (bytes < 0) { > bytes = 0; > - if (uloop_cancelled) > + if (uloop_cancelled || ctx->cancel_poll) > return 0; > if (errno == EINTR) > continue; > @@ -274,7 +275,7 @@ static bool get_next_msg(struct ubus_context *ctx, int *recv_fd) > int r; > > /* receive header + start attribute */ > - r = recv_retry(ctx->sock.fd, &iov, false, recv_fd); > + r = recv_retry(ctx, &iov, false, recv_fd); > if (r <= 0) { > if (r < 0) > ctx->sock.eof = true; > @@ -298,7 +299,7 @@ static bool get_next_msg(struct ubus_context *ctx, int *recv_fd) > iov.iov_base = (char *)ctx->msgbuf.data + sizeof(hdrbuf.data); > iov.iov_len = blob_len(ctx->msgbuf.data); > if (iov.iov_len > 0 && > - recv_retry(ctx->sock.fd, &iov, true, NULL) <= 0) > + recv_retry(ctx, &iov, true, NULL) <= 0) > return false; > > return true; > @@ -311,7 +312,7 @@ void __hidden ubus_handle_data(struct uloop_fd *u, unsigned int events) > > while (get_next_msg(ctx, &recv_fd)) { > ubus_process_msg(ctx, &ctx->msgbuf, recv_fd); > - if (uloop_cancelled) > + if (uloop_cancelled || ctx->cancel_poll) > break; > } > > @@ -326,6 +327,7 @@ void __hidden ubus_poll_data(struct ubus_context *ctx, int timeout) > .events = POLLIN | POLLERR, > }; > > + ctx->cancel_poll = false; > poll(&pfd, 1, timeout ? timeout : -1); > ubus_handle_data(&ctx->sock, ULOOP_READ); > } > diff --git a/libubus-req.c b/libubus-req.c > index db5061c..305e813 100644 > --- a/libubus-req.c > +++ b/libubus-req.c > @@ -122,7 +122,7 @@ static void ubus_sync_req_cb(struct ubus_request *req, int ret) > { > req->status_msg = true; > req->status_code = ret; > - uloop_end(); > + req->ctx->cancel_poll = true; > } > > static int64_t get_time_msec(void) > @@ -142,6 +142,7 @@ int ubus_complete_request(struct ubus_context *ctx, struct ubus_request *req, > ubus_complete_handler_t complete_cb = req->complete_cb; > int status = UBUS_STATUS_NO_DATA; > int64_t timeout = 0, time_end = 0; > + bool prev_uloop_cancelled = uloop_cancelled; > > if (req_timeout) > time_end = get_time_msec() + req_timeout; > @@ -149,29 +150,32 @@ int ubus_complete_request(struct ubus_context *ctx, struct ubus_request *req, > ubus_complete_request_async(ctx, req); > req->complete_cb = ubus_sync_req_cb; > > + if (!ctx->stack_depth) > + uloop_cancelled = false; > + > ctx->stack_depth++; > while (!req->status_msg) { > - bool cancelled = uloop_cancelled; > - > - uloop_cancelled = false; > if (req_timeout) { > timeout = time_end - get_time_msec(); > if (timeout <= 0) { > ubus_set_req_status(req, UBUS_STATUS_TIMEOUT); > - uloop_cancelled = cancelled; > break; > } > } > + > ubus_poll_data(ctx, (unsigned int) timeout); > > - uloop_cancelled = cancelled; > if (ctx->sock.eof) { > ubus_set_req_status(req, UBUS_STATUS_CONNECTION_FAILED); > + ctx->cancel_poll = true; > break; > } > } > + > ctx->stack_depth--; > if (ctx->stack_depth) > + ctx->cancel_poll = true; > + else if (prev_uloop_cancelled) > uloop_cancelled = true; > > if (req->status_msg) > diff --git a/libubus.h b/libubus.h > index ea53272..4e45cb6 100644 > --- a/libubus.h > +++ b/libubus.h > @@ -155,6 +155,7 @@ struct ubus_context { > > uint32_t local_id; > uint16_t request_seq; > + bool cancel_poll; > int stack_depth; > > void (*connection_lost)(struct ubus_context *ctx); >
On 2017-02-03 15:57, Alin Năstac wrote: > Hi Felix, > > The SIGTERM ignore issue I was experiencing before is no longer > reproducible after I apply your patch. > > However, I'm concerned about a possible ignore of SIGTERM signal > received during a ubus_complete_request() call. If ctx->stack_depth is > 0, any such signal received between prev_uloop_initialization and the > reset of ulopp_cancelling to false will be ignored. Is this > "uloop_cancelling = false" really necessary? > > BTW, I think the reset of uloop_status and uloop_cancelled should be > executed before uloop_setup_signals() like so: > if (!recursive_calls++) { > uloop_status = 0; > uloop_cancelled = false; > uloop_setup_signals(true); > } I was worried about the corner case of performing a ubus request after uloop_run has already completed. I guess one way this could be addressed is by setting uloop_cancelled = false at the end of uloop_run(). - Felix
On Fri, Feb 3, 2017 at 4:19 PM, Felix Fietkau <nbd@nbd.name> wrote: > On 2017-02-03 15:57, Alin Năstac wrote: >> Hi Felix, >> >> The SIGTERM ignore issue I was experiencing before is no longer >> reproducible after I apply your patch. >> >> However, I'm concerned about a possible ignore of SIGTERM signal >> received during a ubus_complete_request() call. If ctx->stack_depth is >> 0, any such signal received between prev_uloop_initialization and the >> reset of ulopp_cancelling to false will be ignored. Is this >> "uloop_cancelling = false" really necessary? >> >> BTW, I think the reset of uloop_status and uloop_cancelled should be >> executed before uloop_setup_signals() like so: >> if (!recursive_calls++) { >> uloop_status = 0; >> uloop_cancelled = false; >> uloop_setup_signals(true); >> } > I was worried about the corner case of performing a ubus request after > uloop_run has already completed. > I guess one way this could be addressed is by setting uloop_cancelled = > false at the end of uloop_run(). How about adding this uloop function: static int recursive_calls = 0; /* moved from uloop_run() context */ int uloop_cancelling() { return recursive_calls > 0 && uloop_cancelled; } This function will return true only when uloop_run() is still running, so you will no longer need to touch uloop_cancelled state at all. This way you could reduce the scope of uloop_cancelled to uloop.c too.
On 2017-02-03 16:41, Alin Năstac wrote: > On Fri, Feb 3, 2017 at 4:19 PM, Felix Fietkau <nbd@nbd.name> wrote: >> On 2017-02-03 15:57, Alin Năstac wrote: >>> Hi Felix, >>> >>> The SIGTERM ignore issue I was experiencing before is no longer >>> reproducible after I apply your patch. >>> >>> However, I'm concerned about a possible ignore of SIGTERM signal >>> received during a ubus_complete_request() call. If ctx->stack_depth is >>> 0, any such signal received between prev_uloop_initialization and the >>> reset of ulopp_cancelling to false will be ignored. Is this >>> "uloop_cancelling = false" really necessary? >>> >>> BTW, I think the reset of uloop_status and uloop_cancelled should be >>> executed before uloop_setup_signals() like so: >>> if (!recursive_calls++) { >>> uloop_status = 0; >>> uloop_cancelled = false; >>> uloop_setup_signals(true); >>> } >> I was worried about the corner case of performing a ubus request after >> uloop_run has already completed. >> I guess one way this could be addressed is by setting uloop_cancelled = >> false at the end of uloop_run(). > > How about adding this uloop function: > static int recursive_calls = 0; /* moved from uloop_run() context */ > int uloop_cancelling() > { > return recursive_calls > 0 && uloop_cancelled; > } > > This function will return true only when uloop_run() is still running, > so you will no longer need to touch uloop_cancelled state at all. This > way you could reduce the scope of uloop_cancelled to uloop.c too. Implemented that in libubox.git and ubus.git. Will push to LEDE master soon. Thanks, - Felix
diff --git a/libubus-io.c b/libubus-io.c index 1075c65..1343bb2 100644 --- a/libubus-io.c +++ b/libubus-io.c @@ -154,9 +154,10 @@ int __hidden ubus_send_msg(struct ubus_context *ctx, uint32_t seq, return ret; } -static int recv_retry(int fd, struct iovec *iov, bool wait, int *recv_fd) +static int recv_retry(struct ubus_context *ctx, struct iovec *iov, bool wait, int *recv_fd) { int bytes, total = 0; + int fd = ctx->sock.fd; static struct { struct cmsghdr h; int fd; @@ -191,7 +192,7 @@ static int recv_retry(int fd, struct iovec *iov, bool wait, int *recv_fd) if (bytes < 0) { bytes = 0; - if (uloop_cancelled) + if (uloop_cancelled || ctx->cancel_poll) return 0; if (errno == EINTR) continue; @@ -274,7 +275,7 @@ static bool get_next_msg(struct ubus_context *ctx, int *recv_fd) int r; /* receive header + start attribute */ - r = recv_retry(ctx->sock.fd, &iov, false, recv_fd); + r = recv_retry(ctx, &iov, false, recv_fd); if (r <= 0) { if (r < 0) ctx->sock.eof = true; @@ -298,7 +299,7 @@ static bool get_next_msg(struct ubus_context *ctx, int *recv_fd) iov.iov_base = (char *)ctx->msgbuf.data + sizeof(hdrbuf.data); iov.iov_len = blob_len(ctx->msgbuf.data); if (iov.iov_len > 0 && - recv_retry(ctx->sock.fd, &iov, true, NULL) <= 0) + recv_retry(ctx, &iov, true, NULL) <= 0) return false; return true; @@ -311,7 +312,7 @@ void __hidden ubus_handle_data(struct uloop_fd *u, unsigned int events) while (get_next_msg(ctx, &recv_fd)) { ubus_process_msg(ctx, &ctx->msgbuf, recv_fd); - if (uloop_cancelled) + if (uloop_cancelled || ctx->cancel_poll) break; } @@ -326,6 +327,7 @@ void __hidden ubus_poll_data(struct ubus_context *ctx, int timeout) .events = POLLIN | POLLERR, }; + ctx->cancel_poll = false; poll(&pfd, 1, timeout ? timeout : -1); ubus_handle_data(&ctx->sock, ULOOP_READ); } diff --git a/libubus-req.c b/libubus-req.c index db5061c..305e813 100644 --- a/libubus-req.c +++ b/libubus-req.c @@ -122,7 +122,7 @@ static void ubus_sync_req_cb(struct ubus_request *req, int ret) { req->status_msg = true; req->status_code = ret; - uloop_end(); + req->ctx->cancel_poll = true; } static int64_t get_time_msec(void) @@ -142,6 +142,7 @@ int ubus_complete_request(struct ubus_context *ctx, struct ubus_request *req, ubus_complete_handler_t complete_cb = req->complete_cb; int status = UBUS_STATUS_NO_DATA; int64_t timeout = 0, time_end = 0; + bool prev_uloop_cancelled = uloop_cancelled; if (req_timeout) time_end = get_time_msec() + req_timeout; @@ -149,29 +150,32 @@ int ubus_complete_request(struct ubus_context *ctx, struct ubus_request *req, ubus_complete_request_async(ctx, req); req->complete_cb = ubus_sync_req_cb; + if (!ctx->stack_depth) + uloop_cancelled = false; + ctx->stack_depth++; while (!req->status_msg) { - bool cancelled = uloop_cancelled; - - uloop_cancelled = false; if (req_timeout) { timeout = time_end - get_time_msec(); if (timeout <= 0) { ubus_set_req_status(req, UBUS_STATUS_TIMEOUT); - uloop_cancelled = cancelled; break; } } + ubus_poll_data(ctx, (unsigned int) timeout); - uloop_cancelled = cancelled; if (ctx->sock.eof) { ubus_set_req_status(req, UBUS_STATUS_CONNECTION_FAILED); + ctx->cancel_poll = true; break; } } + ctx->stack_depth--; if (ctx->stack_depth) + ctx->cancel_poll = true; + else if (prev_uloop_cancelled) uloop_cancelled = true; if (req->status_msg) diff --git a/libubus.h b/libubus.h index ea53272..4e45cb6 100644 --- a/libubus.h +++ b/libubus.h @@ -155,6 +155,7 @@ struct ubus_context { uint32_t local_id; uint16_t request_seq; + bool cancel_poll; int stack_depth; void (*connection_lost)(struct ubus_context *ctx);