From owner-svn-ports-all@freebsd.org Thu Mar 30 08:26:07 2017 Return-Path: Delivered-To: svn-ports-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id A0B9FD2320A; Thu, 30 Mar 2017 08:26:07 +0000 (UTC) (envelope-from royger@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 692B2FC9; Thu, 30 Mar 2017 08:26:07 +0000 (UTC) (envelope-from royger@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id v2U8Q6oF059564; Thu, 30 Mar 2017 08:26:06 GMT (envelope-from royger@FreeBSD.org) Received: (from royger@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id v2U8Q6ML059561; Thu, 30 Mar 2017 08:26:06 GMT (envelope-from royger@FreeBSD.org) Message-Id: <201703300826.v2U8Q6ML059561@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: royger set sender to royger@FreeBSD.org using -f From: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= Date: Thu, 30 Mar 2017 08:26:06 +0000 (UTC) To: ports-committers@freebsd.org, svn-ports-all@freebsd.org, svn-ports-branches@freebsd.org Subject: svn commit: r437275 - in branches/2017Q1/sysutils/xen-tools: . files X-SVN-Group: ports-branches MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-ports-all@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: SVN commit messages for the ports tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 30 Mar 2017 08:26:07 -0000 Author: royger (src committer) Date: Thu Mar 30 08:26:06 2017 New Revision: 437275 URL: https://svnweb.freebsd.org/changeset/ports/437275 Log: MFH: r437205 xen: apply XSA-206 Sponsored by: Citrix Systems R&D Differential revision: https://reviews.freebsd.org/D10163 Approved by: ports-secteam (junovitch) Added: branches/2017Q1/sysutils/xen-tools/files/0001-xenstored-apply-a-write-transaction-rate-limit.patch - copied unchanged from r437205, head/sysutils/xen-tools/files/0001-xenstored-apply-a-write-transaction-rate-limit.patch branches/2017Q1/sysutils/xen-tools/files/0002-xenstored-Log-when-the-write-transaction-rate-limit-.patch - copied unchanged from r437205, head/sysutils/xen-tools/files/0002-xenstored-Log-when-the-write-transaction-rate-limit-.patch Modified: branches/2017Q1/sysutils/xen-tools/Makefile Directory Properties: branches/2017Q1/ (props changed) Modified: branches/2017Q1/sysutils/xen-tools/Makefile ============================================================================== --- branches/2017Q1/sysutils/xen-tools/Makefile Thu Mar 30 07:41:50 2017 (r437274) +++ branches/2017Q1/sysutils/xen-tools/Makefile Thu Mar 30 08:26:06 2017 (r437275) @@ -3,7 +3,7 @@ PORTNAME= xen PKGNAMESUFFIX= -tools PORTVERSION= 4.7.2 -PORTREVISION= 0 +PORTREVISION= 1 CATEGORIES= sysutils emulators MASTER_SITES= http://downloads.xenproject.org/release/xen/${PORTVERSION}/ @@ -47,7 +47,9 @@ EXTRA_PATCHES= ${FILESDIR}/var_paths.pat ${FILESDIR}/0001-libxl-fix-creation-of-pkgconf-install-dir.patch:-p1 \ ${FILESDIR}/0001-tools-configure-fix-pkg-config-install-path-for-Free.patch:-p1 \ ${FILESDIR}/0001-libs-xenstore-set-correct-FreeBSD-device.patch:-p1 \ - ${FILESDIR}/kdd.patch:-p1 + ${FILESDIR}/kdd.patch:-p1 \ + ${FILESDIR}/0001-xenstored-apply-a-write-transaction-rate-limit.patch:-p1 \ + ${FILESDIR}/0002-xenstored-Log-when-the-write-transaction-rate-limit-.patch:-p1 CONFIGURE_ARGS+= --with-extra-qemuu-configure-args="${QEMU_ARGS}" \ --with-system-seabios=${LOCALBASE}/share/seabios/bios.bin Copied: branches/2017Q1/sysutils/xen-tools/files/0001-xenstored-apply-a-write-transaction-rate-limit.patch (from r437205, head/sysutils/xen-tools/files/0001-xenstored-apply-a-write-transaction-rate-limit.patch) ============================================================================== --- /dev/null 00:00:00 1970 (empty, because file is newly added) +++ branches/2017Q1/sysutils/xen-tools/files/0001-xenstored-apply-a-write-transaction-rate-limit.patch Thu Mar 30 08:26:06 2017 (r437275, copy of r437205, head/sysutils/xen-tools/files/0001-xenstored-apply-a-write-transaction-rate-limit.patch) @@ -0,0 +1,456 @@ +From bfe42a836450591bb41f4f6393c42dbb0d72abb9 Mon Sep 17 00:00:00 2001 +From: Ian Jackson +Date: Sat, 18 Mar 2017 16:12:26 +0000 +Subject: [PATCH 01/15] xenstored: apply a write transaction rate limit + +This avoids a rogue client being about to stall another client (eg the +toolstack) indefinitely. + +This is XSA-206. + +Signed-off-by: Ian Jackson + +Backported to 4.8 (not entirely trivial). + +Reported-by: Juergen Gross +Signed-off-by: George Dunlap +Acked-by: Ian Jackson +--- + tools/xenstore/Makefile | 3 +- + tools/xenstore/xenstored_core.c | 9 ++ + tools/xenstore/xenstored_core.h | 6 + + tools/xenstore/xenstored_domain.c | 215 +++++++++++++++++++++++++++++++++ + tools/xenstore/xenstored_domain.h | 25 ++++ + tools/xenstore/xenstored_transaction.c | 5 + + 6 files changed, 262 insertions(+), 1 deletion(-) + +diff --git a/tools/xenstore/Makefile b/tools/xenstore/Makefile +index d691b78..b458729 100644 +--- a/tools/xenstore/Makefile ++++ b/tools/xenstore/Makefile +@@ -31,6 +31,7 @@ XENSTORED_OBJS_$(CONFIG_FreeBSD) = xenstored_posix.o + XENSTORED_OBJS_$(CONFIG_MiniOS) = xenstored_minios.o + + XENSTORED_OBJS += $(XENSTORED_OBJS_y) ++LDLIBS_xenstored += -lrt + + ifneq ($(XENSTORE_STATIC_CLIENTS),y) + LIBXENSTORE := libxenstore.so +@@ -72,7 +73,7 @@ endif + $(XENSTORED_OBJS): CFLAGS += $(CFLAGS_libxengnttab) + + xenstored: $(XENSTORED_OBJS) +- $(CC) $^ $(LDFLAGS) $(LDLIBS_libxenevtchn) $(LDLIBS_libxengnttab) $(LDLIBS_libxenctrl) $(SOCKET_LIBS) -o $@ $(APPEND_LDFLAGS) ++ $(CC) $^ $(LDFLAGS) $(LDLIBS_libxenevtchn) $(LDLIBS_libxengnttab) $(LDLIBS_libxenctrl) $(LDLIBS_xenstored) $(SOCKET_LIBS) -o $@ $(APPEND_LDFLAGS) + + xenstored.a: $(XENSTORED_OBJS) + $(AR) cr $@ $^ +diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c +index 51fb0b3..1aabc93 100644 +--- a/tools/xenstore/xenstored_core.c ++++ b/tools/xenstore/xenstored_core.c +@@ -357,6 +357,7 @@ static void initialize_fds(int sock, int *p_sock_pollfd_idx, + int *ptimeout) + { + struct connection *conn; ++ struct wrl_timestampt now; + + if (fds) + memset(fds, 0, sizeof(struct pollfd) * current_array_size); +@@ -376,8 +377,11 @@ static void initialize_fds(int sock, int *p_sock_pollfd_idx, + xce_pollfd_idx = set_fd(xenevtchn_fd(xce_handle), + POLLIN|POLLPRI); + ++ wrl_gettime_now(&now); ++ + list_for_each_entry(conn, &connections, list) { + if (conn->domain) { ++ wrl_check_timeout(conn->domain, now, ptimeout); + if (domain_can_read(conn) || + (domain_can_write(conn) && + !list_empty(&conn->out_list))) +@@ -810,6 +814,7 @@ static void delete_node_single(struct connection *conn, struct node *node) + corrupt(conn, "Could not delete '%s'", node->name); + return; + } ++ + domain_entry_dec(conn, node); + } + +@@ -949,6 +954,7 @@ static void do_write(struct connection *conn, struct buffered_data *in) + } + + add_change_node(conn->transaction, name, false); ++ wrl_apply_debit_direct(conn); + fire_watches(conn, name, false); + send_ack(conn, XS_WRITE); + } +@@ -973,6 +979,7 @@ static void do_mkdir(struct connection *conn, const char *name) + return; + } + add_change_node(conn->transaction, name, false); ++ wrl_apply_debit_direct(conn); + fire_watches(conn, name, false); + } + send_ack(conn, XS_MKDIR); +@@ -1098,6 +1105,7 @@ static void do_rm(struct connection *conn, const char *name) + + if (_rm(conn, node, name)) { + add_change_node(conn->transaction, name, true); ++ wrl_apply_debit_direct(conn); + fire_watches(conn, name, true); + send_ack(conn, XS_RM); + } +@@ -1173,6 +1181,7 @@ static void do_set_perms(struct connection *conn, struct buffered_data *in) + } + + add_change_node(conn->transaction, name, false); ++ wrl_apply_debit_direct(conn); + fire_watches(conn, name, false); + send_ack(conn, XS_SET_PERMS); + } +diff --git a/tools/xenstore/xenstored_core.h b/tools/xenstore/xenstored_core.h +index 3a497f7..a2a3427 100644 +--- a/tools/xenstore/xenstored_core.h ++++ b/tools/xenstore/xenstored_core.h +@@ -33,6 +33,12 @@ + #include "list.h" + #include "tdb.h" + ++#define MIN(a, b) (((a) < (b))? (a) : (b)) ++ ++typedef int32_t wrl_creditt; ++#define WRL_CREDIT_MAX (1000*1000*1000) ++/* ^ satisfies non-overflow condition for wrl_xfer_credit */ ++ + struct buffered_data + { + struct list_head list; +diff --git a/tools/xenstore/xenstored_domain.c b/tools/xenstore/xenstored_domain.c +index 47b4f03..486c96f 100644 +--- a/tools/xenstore/xenstored_domain.c ++++ b/tools/xenstore/xenstored_domain.c +@@ -21,6 +21,7 @@ + #include + #include + #include ++#include + + #include "utils.h" + #include "talloc.h" +@@ -74,6 +75,10 @@ struct domain + + /* number of watch for this domain */ + int nbwatch; ++ ++ /* write rate limit */ ++ wrl_creditt wrl_credit; /* [ -wrl_config_writecost, +_dburst ] */ ++ struct wrl_timestampt wrl_timestamp; + }; + + static LIST_HEAD(domains); +@@ -206,6 +211,8 @@ static int destroy_domain(void *_domain) + + fire_watches(NULL, "@releaseDomain", false); + ++ wrl_domain_destroy(domain); ++ + return 0; + } + +@@ -253,6 +260,9 @@ void handle_event(void) + bool domain_can_read(struct connection *conn) + { + struct xenstore_domain_interface *intf = conn->domain->interface; ++ ++ if (domain_is_unprivileged(conn) && conn->domain->wrl_credit < 0) ++ return false; + return (intf->req_cons != intf->req_prod); + } + +@@ -284,6 +294,8 @@ static struct domain *new_domain(void *context, unsigned int domid, + domain->domid = domid; + domain->path = talloc_domain_path(domain, domid); + ++ wrl_domain_new(domain); ++ + list_add(&domain->list, &domains); + talloc_set_destructor(domain, destroy_domain); + +@@ -747,6 +759,209 @@ int domain_watch(struct connection *conn) + : 0; + } + ++static wrl_creditt wrl_config_writecost = WRL_FACTOR; ++static wrl_creditt wrl_config_rate = WRL_RATE * WRL_FACTOR; ++static wrl_creditt wrl_config_dburst = WRL_DBURST * WRL_FACTOR; ++static wrl_creditt wrl_config_gburst = WRL_GBURST * WRL_FACTOR; ++static wrl_creditt wrl_config_newdoms_dburst = ++ WRL_DBURST * WRL_NEWDOMS * WRL_FACTOR; ++ ++long wrl_ntransactions; ++ ++static long wrl_ndomains; ++static wrl_creditt wrl_reserve; /* [-wrl_config_newdoms_dburst, +_gburst ] */ ++ ++void wrl_gettime_now(struct wrl_timestampt *now_wt) ++{ ++ struct timespec now_ts; ++ int r; ++ ++ r = clock_gettime(CLOCK_MONOTONIC, &now_ts); ++ if (r) ++ barf_perror("Could not find time (clock_gettime failed)"); ++ ++ now_wt->sec = now_ts.tv_sec; ++ now_wt->msec = now_ts.tv_nsec / 1000000; ++} ++ ++static void wrl_xfer_credit(wrl_creditt *debit, wrl_creditt debit_floor, ++ wrl_creditt *credit, wrl_creditt credit_ceil) ++ /* ++ * Transfers zero or more credit from "debit" to "credit". ++ * Transfers as much as possible while maintaining ++ * debit >= debit_floor and credit <= credit_ceil. ++ * (If that's violated already, does nothing.) ++ * ++ * Sufficient conditions to avoid overflow, either of: ++ * |every argument| <= 0x3fffffff ++ * |every argument| <= 1E9 ++ * |every argument| <= WRL_CREDIT_MAX ++ * (And this condition is preserved.) ++ */ ++{ ++ wrl_creditt xfer = MIN( *debit - debit_floor, ++ credit_ceil - *credit ); ++ if (xfer > 0) { ++ *debit -= xfer; ++ *credit += xfer; ++ } ++} ++ ++void wrl_domain_new(struct domain *domain) ++{ ++ domain->wrl_credit = 0; ++ wrl_gettime_now(&domain->wrl_timestamp); ++ wrl_ndomains++; ++ /* Steal up to DBURST from the reserve */ ++ wrl_xfer_credit(&wrl_reserve, -wrl_config_newdoms_dburst, ++ &domain->wrl_credit, wrl_config_dburst); ++} ++ ++void wrl_domain_destroy(struct domain *domain) ++{ ++ wrl_ndomains--; ++ /* ++ * Don't bother recalculating domain's credit - this just ++ * means we don't give the reserve the ending domain's credit ++ * for time elapsed since last update. ++ */ ++ wrl_xfer_credit(&domain->wrl_credit, 0, ++ &wrl_reserve, wrl_config_dburst); ++} ++ ++void wrl_credit_update(struct domain *domain, struct wrl_timestampt now) ++{ ++ /* ++ * We want to calculate ++ * credit += (now - timestamp) * RATE / ndoms; ++ * But we want it to saturate, and to avoid floating point. ++ * To avoid rounding errors from constantly adding small ++ * amounts of credit, we only add credit for whole milliseconds. ++ */ ++ long seconds = now.sec - domain->wrl_timestamp.sec; ++ long milliseconds = now.msec - domain->wrl_timestamp.msec; ++ long msec; ++ int64_t denom, num; ++ wrl_creditt surplus; ++ ++ seconds = MIN(seconds, 1000*1000); /* arbitrary, prevents overflow */ ++ msec = seconds * 1000 + milliseconds; ++ ++ if (msec < 0) ++ /* shouldn't happen with CLOCK_MONOTONIC */ ++ msec = 0; ++ ++ /* 32x32 -> 64 cannot overflow */ ++ denom = (int64_t)msec * wrl_config_rate; ++ num = (int64_t)wrl_ndomains * 1000; ++ /* denom / num <= 1E6 * wrl_config_rate, so with ++ reasonable wrl_config_rate, denom / num << 2^64 */ ++ ++ /* at last! */ ++ domain->wrl_credit = MIN( (int64_t)domain->wrl_credit + denom / num, ++ WRL_CREDIT_MAX ); ++ /* (maybe briefly violating the DBURST cap on wrl_credit) */ ++ ++ /* maybe take from the reserve to make us nonnegative */ ++ wrl_xfer_credit(&wrl_reserve, 0, ++ &domain->wrl_credit, 0); ++ ++ /* return any surplus (over DBURST) to the reserve */ ++ surplus = 0; ++ wrl_xfer_credit(&domain->wrl_credit, wrl_config_dburst, ++ &surplus, WRL_CREDIT_MAX); ++ wrl_xfer_credit(&surplus, 0, ++ &wrl_reserve, wrl_config_gburst); ++ /* surplus is now implicitly discarded */ ++ ++ domain->wrl_timestamp = now; ++ ++ trace("wrl: dom %4d %6ld msec %9ld credit %9ld reserve" ++ " %9ld discard\n", ++ domain->domid, ++ msec, ++ (long)domain->wrl_credit, (long)wrl_reserve, ++ (long)surplus); ++} ++ ++void wrl_check_timeout(struct domain *domain, ++ struct wrl_timestampt now, ++ int *ptimeout) ++{ ++ uint64_t num, denom; ++ int wakeup; ++ ++ wrl_credit_update(domain, now); ++ ++ if (domain->wrl_credit >= 0) ++ /* not blocked */ ++ return; ++ ++ if (!*ptimeout) ++ /* already decided on immediate wakeup, ++ so no need to calculate our timeout */ ++ return; ++ ++ /* calculate wakeup = now + -credit / (RATE / ndoms); */ ++ ++ /* credit cannot go more -ve than one transaction, ++ * so the first multiplication cannot overflow even 32-bit */ ++ num = (uint64_t)(-domain->wrl_credit * 1000) * wrl_ndomains; ++ denom = wrl_config_rate; ++ ++ wakeup = MIN( num / denom /* uint64_t */, INT_MAX ); ++ if (*ptimeout==-1 || wakeup < *ptimeout) ++ *ptimeout = wakeup; ++ ++ trace("wrl: domain %u credit=%ld (reserve=%ld) SLEEPING for %d\n", ++ domain->domid, ++ (long)domain->wrl_credit, (long)wrl_reserve, ++ wakeup); ++} ++ ++void wrl_apply_debit_actual(struct domain *domain) ++{ ++ struct wrl_timestampt now; ++ ++ if (!domain) ++ /* sockets escape the write rate limit */ ++ return; ++ ++ wrl_gettime_now(&now); ++ wrl_credit_update(domain, now); ++ ++ domain->wrl_credit -= wrl_config_writecost; ++ trace("wrl: domain %u credit=%ld (reserve=%ld)\n", ++ domain->domid, ++ (long)domain->wrl_credit, (long)wrl_reserve); ++} ++ ++void wrl_apply_debit_direct(struct connection *conn) ++{ ++ if (!conn) ++ /* some writes are generated internally */ ++ return; ++ ++ if (conn->transaction) ++ /* these are accounted for when the transaction ends */ ++ return; ++ ++ if (!wrl_ntransactions) ++ /* we don't conflict with anyone */ ++ return; ++ ++ wrl_apply_debit_actual(conn->domain); ++} ++ ++void wrl_apply_debit_trans_commit(struct connection *conn) ++{ ++ if (wrl_ntransactions <= 1) ++ /* our own transaction appears in the counter */ ++ return; ++ ++ wrl_apply_debit_actual(conn->domain); ++} ++ + /* + * Local variables: + * c-file-style: "linux" +diff --git a/tools/xenstore/xenstored_domain.h b/tools/xenstore/xenstored_domain.h +index 83488ed..bdc4044 100644 +--- a/tools/xenstore/xenstored_domain.h ++++ b/tools/xenstore/xenstored_domain.h +@@ -65,4 +65,29 @@ void domain_watch_inc(struct connection *conn); + void domain_watch_dec(struct connection *conn); + int domain_watch(struct connection *conn); + ++/* Write rate limiting */ ++ ++#define WRL_FACTOR 1000 /* for fixed-point arithmetic */ ++#define WRL_RATE 200 ++#define WRL_DBURST 10 ++#define WRL_GBURST 1000 ++#define WRL_NEWDOMS 5 ++ ++struct wrl_timestampt { ++ time_t sec; ++ int msec; ++}; ++ ++extern long wrl_ntransactions; ++ ++void wrl_gettime_now(struct wrl_timestampt *now_ts); ++void wrl_domain_new(struct domain *domain); ++void wrl_domain_destroy(struct domain *domain); ++void wrl_credit_update(struct domain *domain, struct wrl_timestampt now); ++void wrl_check_timeout(struct domain *domain, ++ struct wrl_timestampt now, ++ int *ptimeout); ++void wrl_apply_debit_direct(struct connection *conn); ++void wrl_apply_debit_trans_commit(struct connection *conn); ++ + #endif /* _XENSTORED_DOMAIN_H */ +diff --git a/tools/xenstore/xenstored_transaction.c b/tools/xenstore/xenstored_transaction.c +index d0e4739..a4b328f 100644 +--- a/tools/xenstore/xenstored_transaction.c ++++ b/tools/xenstore/xenstored_transaction.c +@@ -116,6 +116,7 @@ static int destroy_transaction(void *_transaction) + { + struct transaction *trans = _transaction; + ++ wrl_ntransactions--; + trace_destroy(trans, "transaction"); + if (trans->tdb) + tdb_close(trans->tdb); +@@ -179,6 +180,7 @@ void do_transaction_start(struct connection *conn, struct buffered_data *in) + talloc_steal(conn, trans); + talloc_set_destructor(trans, destroy_transaction); + conn->transaction_started++; ++ wrl_ntransactions++; + + snprintf(id_str, sizeof(id_str), "%u", trans->id); + send_reply(conn, XS_TRANSACTION_START, id_str, strlen(id_str)+1); +@@ -213,6 +215,9 @@ void do_transaction_end(struct connection *conn, const char *arg) + send_error(conn, EAGAIN); + return; + } ++ ++ wrl_apply_debit_trans_commit(conn); ++ + if (!replace_tdb(trans->tdb_name, trans->tdb)) { + send_error(conn, errno); + return; +-- +2.1.4 + Copied: branches/2017Q1/sysutils/xen-tools/files/0002-xenstored-Log-when-the-write-transaction-rate-limit-.patch (from r437205, head/sysutils/xen-tools/files/0002-xenstored-Log-when-the-write-transaction-rate-limit-.patch) ============================================================================== --- /dev/null 00:00:00 1970 (empty, because file is newly added) +++ branches/2017Q1/sysutils/xen-tools/files/0002-xenstored-Log-when-the-write-transaction-rate-limit-.patch Thu Mar 30 08:26:06 2017 (r437275, copy of r437205, head/sysutils/xen-tools/files/0002-xenstored-Log-when-the-write-transaction-rate-limit-.patch) @@ -0,0 +1,113 @@ +From 1d713bf29548ee3e48c3170bafe2863d17694e90 Mon Sep 17 00:00:00 2001 +From: Ian Jackson +Date: Sat, 18 Mar 2017 16:39:31 +0000 +Subject: [PATCH 02/15] xenstored: Log when the write transaction rate limit + bites + +Reported-by: Juergen Gross +Signed-off-by: Ian Jackson +--- + tools/xenstore/xenstored_core.c | 1 + + tools/xenstore/xenstored_domain.c | 25 +++++++++++++++++++++++++ + tools/xenstore/xenstored_domain.h | 2 ++ + 3 files changed, 28 insertions(+) + +diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c +index 1aabc93..907b44f 100644 +--- a/tools/xenstore/xenstored_core.c ++++ b/tools/xenstore/xenstored_core.c +@@ -378,6 +378,7 @@ static void initialize_fds(int sock, int *p_sock_pollfd_idx, + POLLIN|POLLPRI); + + wrl_gettime_now(&now); ++ wrl_log_periodic(now); + + list_for_each_entry(conn, &connections, list) { + if (conn->domain) { +diff --git a/tools/xenstore/xenstored_domain.c b/tools/xenstore/xenstored_domain.c +index 486c96f..75cfad1 100644 +--- a/tools/xenstore/xenstored_domain.c ++++ b/tools/xenstore/xenstored_domain.c +@@ -22,6 +22,7 @@ + #include + #include + #include ++#include + + #include "utils.h" + #include "talloc.h" +@@ -79,6 +80,7 @@ struct domain + /* write rate limit */ + wrl_creditt wrl_credit; /* [ -wrl_config_writecost, +_dburst ] */ + struct wrl_timestampt wrl_timestamp; ++ bool wrl_delay_logged; + }; + + static LIST_HEAD(domains); +@@ -770,6 +772,7 @@ long wrl_ntransactions; + + static long wrl_ndomains; + static wrl_creditt wrl_reserve; /* [-wrl_config_newdoms_dburst, +_gburst ] */ ++static time_t wrl_log_last_warning; /* 0: no previous warning */ + + void wrl_gettime_now(struct wrl_timestampt *now_wt) + { +@@ -919,6 +922,9 @@ void wrl_check_timeout(struct domain *domain, + wakeup); + } + ++#define WRL_LOG(now, ...) \ ++ (syslog(LOG_WARNING, "write rate limit: " __VA_ARGS__)) ++ + void wrl_apply_debit_actual(struct domain *domain) + { + struct wrl_timestampt now; +@@ -934,6 +940,25 @@ void wrl_apply_debit_actual(struct domain *domain) + trace("wrl: domain %u credit=%ld (reserve=%ld)\n", + domain->domid, + (long)domain->wrl_credit, (long)wrl_reserve); ++ ++ if (domain->wrl_credit < 0) { ++ if (!domain->wrl_delay_logged++) { ++ WRL_LOG(now, "domain %ld is affected", ++ (long)domain->domid); ++ } else if (!wrl_log_last_warning) { ++ WRL_LOG(now, "rate limiting restarts"); ++ } ++ wrl_log_last_warning = now.sec; ++ } ++} ++ ++void wrl_log_periodic(struct wrl_timestampt now) ++{ ++ if (wrl_log_last_warning && ++ (now.sec - wrl_log_last_warning) > WRL_LOGEVERY) { ++ WRL_LOG(now, "not in force recently"); ++ wrl_log_last_warning = 0; ++ } + } + + void wrl_apply_debit_direct(struct connection *conn) +diff --git a/tools/xenstore/xenstored_domain.h b/tools/xenstore/xenstored_domain.h +index bdc4044..2b963ed 100644 +--- a/tools/xenstore/xenstored_domain.h ++++ b/tools/xenstore/xenstored_domain.h +@@ -72,6 +72,7 @@ int domain_watch(struct connection *conn); + #define WRL_DBURST 10 + #define WRL_GBURST 1000 + #define WRL_NEWDOMS 5 ++#define WRL_LOGEVERY 120 /* seconds */ + + struct wrl_timestampt { + time_t sec; +@@ -87,6 +88,7 @@ void wrl_credit_update(struct domain *domain, struct wrl_timestampt now); + void wrl_check_timeout(struct domain *domain, + struct wrl_timestampt now, + int *ptimeout); ++void wrl_log_periodic(struct wrl_timestampt now); + void wrl_apply_debit_direct(struct connection *conn); + void wrl_apply_debit_trans_commit(struct connection *conn); + +-- +2.1.4 +