linux-kernel - [PATCH] zs.c: Drain the transmission line

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Date:	Wed, 6 Jun 2007 10:07:34 +0100 (BST)
From:	"Maciej W. Rozycki" <macro@...ux-mips.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
cc:	linux-mips@...ux-mips.org, linux-serial@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] zs.c: Drain the transmission line

 This is an update to the zs.c driver to make it wait for the transmission 
line to become idle before disabling the transmitter or resetting the 
chip.  This way the character that is on the way at the time one of these 
actions is about to be performed does not get corrupted.

 Plus a change to reset the index/data pointer first before issuing a chip 
reset just in case the state is wrong when control of the chip is taken 
the first time.

Signed-off-by: Maciej W. Rozycki <macro@...ux-mips.org>
---
 These are almost obvious, but I have run-time tested them just in case.  
They make the switch from the initial (early printk) PROM-based console 
less disruptive.  The change to load_zsregs() also affects set_termios().

 Please apply,

  Maciej

patch-mips-2.6.21-20070502-zs-serial-drain-3
diff -up --recursive --new-file linux-mips-2.6.21-20070502.macro/drivers/serial/zs.c linux-mips-2.6.21-20070502/drivers/serial/zs.c
--- linux-mips-2.6.21-20070502.macro/drivers/serial/zs.c	2007-06-05 11:08:24.000000000 +0000
+++ linux-mips-2.6.21-20070502/drivers/serial/zs.c	2007-06-05 11:08:57.000000000 +0000
@@ -240,10 +240,24 @@ static int zs_transmit_drain(struct zs_p
 	return loops;
 }
 
+static int zs_line_drain(struct zs_port *zport, int irq)
+{
+	struct zs_scc *scc = zport->scc;
+	int loops = 10000;
+
+	while (!(read_zsreg(zport, R1) & ALL_SNT) && loops--) {
+		zs_spin_unlock_cond_irq(&scc->zlock, irq);
+		udelay(2);
+		zs_spin_lock_cond_irq(&scc->zlock, irq);
+	}
+	return loops;
+}
+
 
 static void load_zsregs(struct zs_port *zport, u8 *regs, int irq)
 {
-	zs_transmit_drain(zport, irq);
+	/* Let the current transmission finish.  */
+	zs_line_drain(zport, irq);
 	/* Load 'em up.  */
 	write_zsreg(zport, R3, regs[3] & ~RxENABLE);
 	write_zsreg(zport, R5, regs[5] & ~TxENAB);
@@ -814,6 +828,10 @@ static void zs_reset(struct zs_port *zpo
 	spin_lock_irqsave(&scc->zlock, flags);
 	irq = !irqs_disabled_flags(flags);
 	if (!scc->initialised) {
+		/* Reset the pointer first, just in case...  */
+		read_zsreg(zport, R0);
+		/* And let the current transmission finish.  */
+		zs_line_drain(zport, irq);
 		write_zsreg(zport, R9, FHWRES);
 		udelay(10);
 		write_zsreg(zport, R9, 0);
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/