From 0f9e5b573f7249b0e04a03457b55081d1f60f2bf Mon Sep 17 00:00:00 2001 From: Gerrit Renker Date: Sun, 10 Dec 2006 00:03:51 -0200 Subject: [DCCP]: Debug timeval operations Problem: Most target types in the CCID3 code are u32, so subtle conversion errors can occur if signed time calculations yield negative results: the original values are lost in the conversion to unsigned, calculation errors go undetected. This patch therefore * sets all critical time types from unsigned to suseconds_t * avoids comparison between signed/unsigned via type-casting * provides ample warning messages in case time calculations are negative These warning messages can be removed at a later stage when the code has undergone more testing. Signed-off-by: Gerrit Renker Acked-by: Ian McDonald Signed-off-by: Arnaldo Carvalho de Melo --- net/dccp/ccids/ccid3.c | 56 ++++++++++++++++++++++++++++---------------------- net/dccp/dccp.h | 1 + 2 files changed, 33 insertions(+), 24 deletions(-) diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c index 89ef1183e48c..820bc25e14dc 100644 --- a/net/dccp/ccids/ccid3.c +++ b/net/dccp/ccids/ccid3.c @@ -128,8 +128,8 @@ static void ccid3_hc_tx_update_x(struct sock *sk, struct timeval *now) hctx->ccid3hctx_x = max_t(u64, hctx->ccid3hctx_x, (hctx->ccid3hctx_s << 6)/TFRC_T_MBI); - } else if (timeval_delta(now, &hctx->ccid3hctx_t_ld) >= - hctx->ccid3hctx_rtt) { + } else if (timeval_delta(now, &hctx->ccid3hctx_t_ld) - + (suseconds_t)hctx->ccid3hctx_rtt >= 0 ) { hctx->ccid3hctx_x = max(2 * min(hctx->ccid3hctx_x, hctx->ccid3hctx_x_recv), @@ -271,7 +271,7 @@ static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb) struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk); struct dccp_tx_hist_entry *new_packet; struct timeval now; - long delay; + suseconds_t delay; BUG_ON(hctx == NULL); @@ -331,7 +331,7 @@ static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb) * else * // send the packet in (t_nom - t_now) milliseconds. */ - if (delay - (long)hctx->ccid3hctx_delta >= 0) + if (delay - (suseconds_t)hctx->ccid3hctx_delta >= 0) return delay / 1000L; break; case TFRC_SSTATE_TERM: @@ -353,7 +353,7 @@ static void ccid3_hc_tx_packet_sent(struct sock *sk, int more, unsigned int len) const struct dccp_sock *dp = dccp_sk(sk); struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk); struct timeval now; - unsigned long quarter_rtt; + suseconds_t quarter_rtt; struct dccp_tx_hist_entry *packet; BUG_ON(hctx == NULL); @@ -450,10 +450,8 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) r_sample = timeval_delta(&now, &packet->dccphtx_tstamp); t_elapsed = dp->dccps_options_received.dccpor_elapsed_time * 10; - if (unlikely(r_sample <= 0)) { - DCCP_WARN("WARNING: R_sample (%ld) <= 0!\n", r_sample); - r_sample = 0; - } else if (unlikely(r_sample <= t_elapsed)) + DCCP_BUG_ON(r_sample < 0); + if (unlikely(r_sample <= t_elapsed)) DCCP_WARN("WARNING: r_sample=%ldus <= t_elapsed=%ldus\n", r_sample, t_elapsed); else @@ -698,6 +696,7 @@ static void ccid3_hc_rx_send_feedback(struct sock *sk) struct dccp_sock *dp = dccp_sk(sk); struct dccp_rx_hist_entry *packet; struct timeval now; + suseconds_t delta; ccid3_pr_debug("%s, sk=%p\n", dccp_role(sk), sk); @@ -707,12 +706,12 @@ static void ccid3_hc_rx_send_feedback(struct sock *sk) case TFRC_RSTATE_NO_DATA: hcrx->ccid3hcrx_x_recv = 0; break; - case TFRC_RSTATE_DATA: { - const u32 delta = timeval_delta(&now, - &hcrx->ccid3hcrx_tstamp_last_feedback); + case TFRC_RSTATE_DATA: + delta = timeval_delta(&now, + &hcrx->ccid3hcrx_tstamp_last_feedback); + DCCP_BUG_ON(delta < 0); hcrx->ccid3hcrx_x_recv = scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta); - } break; case TFRC_RSTATE_TERM: DCCP_BUG("Illegal %s state TERM, sk=%p", dccp_role(sk), sk); @@ -730,9 +729,10 @@ static void ccid3_hc_rx_send_feedback(struct sock *sk) hcrx->ccid3hcrx_ccval_last_counter = packet->dccphrx_ccval; hcrx->ccid3hcrx_bytes_recv = 0; - /* Convert to multiples of 10us */ - hcrx->ccid3hcrx_elapsed_time = - timeval_delta(&now, &packet->dccphrx_tstamp) / 10; + /* Elapsed time information [RFC 4340, 13.2] in units of 10 * usecs */ + delta = timeval_delta(&now, &packet->dccphrx_tstamp); + DCCP_BUG_ON(delta < 0); + hcrx->ccid3hcrx_elapsed_time = delta / 10; if (hcrx->ccid3hcrx_p == 0) hcrx->ccid3hcrx_pinv = ~0U; /* see RFC 4342, 8.5 */ @@ -785,7 +785,8 @@ static u32 ccid3_hc_rx_calc_first_li(struct sock *sk) { struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk); struct dccp_rx_hist_entry *entry, *next, *tail = NULL; - u32 rtt, delta, x_recv, p; + u32 x_recv, p; + suseconds_t rtt, delta; struct timeval tstamp = { 0, }; int interval = 0; int win_count = 0; @@ -830,8 +831,12 @@ found: DCCP_CRIT("tail is null\n"); return ~0; } - rtt = timeval_delta(&tstamp, &tail->dccphrx_tstamp) * 4 / interval; - ccid3_pr_debug("%s, sk=%p, approximated RTT to %uus\n", + + delta = timeval_delta(&tstamp, &tail->dccphrx_tstamp); + DCCP_BUG_ON(delta < 0); + + rtt = delta * 4 / interval; + ccid3_pr_debug("%s, sk=%p, approximated RTT to %ldus\n", dccp_role(sk), sk, rtt); /* @@ -849,8 +854,9 @@ found: dccp_timestamp(sk, &tstamp); delta = timeval_delta(&tstamp, &hcrx->ccid3hcrx_tstamp_last_feedback); - x_recv = scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta); + DCCP_BUG_ON(delta <= 0); + x_recv = scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta); if (x_recv == 0) { /* would also trigger divide-by-zero */ DCCP_WARN("X_recv==0\n"); if ((x_recv = hcrx->ccid3hcrx_x_recv) == 0) { @@ -977,7 +983,8 @@ static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb) const struct dccp_options_received *opt_recv; struct dccp_rx_hist_entry *packet; struct timeval now; - u32 p_prev, rtt_prev, r_sample, t_elapsed; + u32 p_prev, rtt_prev; + suseconds_t r_sample, t_elapsed; int loss, payload_size; BUG_ON(hcrx == NULL); @@ -997,8 +1004,9 @@ static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb) r_sample = timeval_usecs(&now); t_elapsed = opt_recv->dccpor_elapsed_time * 10; + DCCP_BUG_ON(r_sample < 0); if (unlikely(r_sample <= t_elapsed)) - DCCP_WARN("r_sample=%uus, t_elapsed=%uus\n", + DCCP_WARN("r_sample=%ldus, t_elapsed=%ldus\n", r_sample, t_elapsed); else r_sample -= t_elapsed; @@ -1051,8 +1059,8 @@ static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb) break; dccp_timestamp(sk, &now); - if (timeval_delta(&now, &hcrx->ccid3hcrx_tstamp_last_ack) >= - hcrx->ccid3hcrx_rtt) { + if (timeval_delta(&now, &hcrx->ccid3hcrx_tstamp_last_ack) - + (suseconds_t)hcrx->ccid3hcrx_rtt >= 0) { hcrx->ccid3hcrx_tstamp_last_ack = now; ccid3_hc_rx_send_feedback(sk); } diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h index 44829d636c93..a0900bf98e6b 100644 --- a/net/dccp/dccp.h +++ b/net/dccp/dccp.h @@ -432,6 +432,7 @@ static inline void timeval_sub_usecs(struct timeval *tv, tv->tv_sec--; tv->tv_usec += USEC_PER_SEC; } + DCCP_BUG_ON(tv->tv_sec < 0); } #ifdef CONFIG_SYSCTL -- cgit v1.2.2