netdev - [PATCH 1/2] [Patch v2] [CCID2/3]: Fix sparse warnings

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Message-Id: <1207043051-27165-2-git-send-email-gerrit@erg.abdn.ac.uk>
Date:	Tue,  1 Apr 2008 10:44:10 +0100
From:	Gerrit Renker <gerrit@....abdn.ac.uk>
To:	acme@...hat.com
Cc:	dccp@...r.kernel.org, netdev@...r.kernel.org,
	Gerrit Renker <gerrit@....abdn.ac.uk>
Subject: [PATCH 1/2] [Patch v2] [CCID2/3]: Fix sparse warnings

This is revision 2 of the patch. The first revision had a bug: the 
"if (x < low_thresh)" appeared in the main control flow so that if p == 0
and t_now - t_ld < RTT, x was reduced to 1 packet per second. This is
fixed now by making the test dependent on whether X was actually changed.

---------------------> Patch v2 <---------------------------------------------

This patch fixes the following two sparse warnings:

 1. Due to a nested min(max()) expression, sparse gave the following warnings:

    net/dccp/ccids/ccid3.c:91:21: warning: symbol '__x' shadows an earlier one
    net/dccp/ccids/ccid3.c:91:21: warning: symbol '__y' shadows an earlier one

    In addition, in update_x(), the function call to scaled_div() appeared as
    macro parameter and was thus evaluated multiple times.
    Fixed by disentangling the nested expression - code also clearer now.

 2. Declaration of function prototypes was in .c instead of .h file.
    This resulted in "should it be static" warnings. Corrected by moving the
    declarations to the tfrc.h file instead of the tfrc.c file.

Signed-off-by: Gerrit Renker <gerrit@....abdn.ac.uk>
---
 net/dccp/ccids/ccid3.c    |   12 ++++++++----
 net/dccp/ccids/lib/tfrc.c |    8 --------
 net/dccp/ccids/lib/tfrc.h |   11 +++++++++--
 3 files changed, 17 insertions(+), 14 deletions(-)

--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -129,7 +129,8 @@ static u32 ccid3_hc_tx_idle_rtt(struct ccid3_hc_tx_sock *hctx, ktime_t now)
 static void ccid3_hc_tx_update_x(struct sock *sk, ktime_t *stamp)
 {
 	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
-	u64 min_rate = 2 * hctx->x_recv;
+	u64 min_rate = 2 * hctx->x_recv,
+	    low_thresh = ((u64)hctx->s) << 6;
 	const u64 old_x = hctx->x;
 	ktime_t now = stamp ? *stamp : ktime_get_real();
 
@@ -147,16 +148,19 @@ static void ccid3_hc_tx_update_x(struct sock *sk, ktime_t *stamp)
 	if (hctx->p > 0) {
 
 		hctx->x = min(((u64)hctx->x_calc) << 6, min_rate);
-		hctx->x = max(hctx->x, (((u64)hctx->s) << 6) / TFRC_T_MBI);
+		low_thresh /= TFRC_T_MBI;
 
 	} else if (ktime_us_delta(now, hctx->t_ld) - (s64)hctx->rtt >= 0) {
 
-		hctx->x = max(min(2 * hctx->x, min_rate),
-			      scaled_div(((u64)hctx->s) << 6, hctx->rtt));
+		hctx->x    = min(2 * old_x, min_rate);
+		low_thresh = scaled_div(low_thresh, hctx->rtt);
 		hctx->t_ld = now;
 	}
 
 	if (hctx->x != old_x) {
+		if (hctx->x < low_thresh)
+			hctx->x = low_thresh;
+
 		ccid3_pr_debug("X_prev=%u, X_now=%u, X_calc=%u, "
 			       "X_recv=%u\n", (unsigned)(old_x >> 6),
 			       (unsigned)(hctx->x >> 6), hctx->x_calc,
--- a/net/dccp/ccids/lib/tfrc.c
+++ b/net/dccp/ccids/lib/tfrc.c
@@ -14,14 +14,6 @@ module_param(tfrc_debug, bool, 0444);
 MODULE_PARM_DESC(tfrc_debug, "Enable debug messages");
 #endif
 
-extern int  tfrc_tx_packet_history_init(void);
-extern void tfrc_tx_packet_history_exit(void);
-extern int  tfrc_rx_packet_history_init(void);
-extern void tfrc_rx_packet_history_exit(void);
-
-extern int  tfrc_li_init(void);
-extern void tfrc_li_exit(void);
-
 static int __init tfrc_module_init(void)
 {
 	int rc = tfrc_li_init();
--- a/net/dccp/ccids/lib/tfrc.h
+++ b/net/dccp/ccids/lib/tfrc.h
@@ -58,7 +58,14 @@ static inline u32 tfrc_ewma(const u32 avg, const u32 newval, const u8 weight)
 	return avg ? (weight * avg + (10 - weight) * newval) / 10 : newval;
 }
 
-extern u32 tfrc_calc_x(u16 s, u32 R, u32 p);
-extern u32 tfrc_calc_x_reverse_lookup(u32 fvalue);
+extern u32  tfrc_calc_x(u16 s, u32 R, u32 p);
+extern u32  tfrc_calc_x_reverse_lookup(u32 fvalue);
 
+extern int  tfrc_tx_packet_history_init(void);
+extern void tfrc_tx_packet_history_exit(void);
+extern int  tfrc_rx_packet_history_init(void);
+extern void tfrc_rx_packet_history_exit(void);
+
+extern int  tfrc_li_init(void);
+extern void tfrc_li_exit(void);
 #endif /* _TFRC_H_ */
-- 
1.5.3.GIT



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