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Date: Tue, 18 May 2010 20:39:20 -0500
From: Jason Wessel <jason.wessel@...driver.com>
To: torvalds@...ux-foundation.org
Cc: linux-kernel@...r.kernel.org, kgdb-bugreport@...ts.sourceforge.net,
Jason Wessel <jason.wessel@...driver.com>,
linux-serial@...r.kernel.org
Subject: [PATCH 10/25] kgdb,8250,pl011: Return immediately from console poll
The design of the kdb shell requires that every device that can
provide input to kdb have a polling routine that exits immediately if
there is no character available. This is required in order to get the
page scrolling mechanism working.
Changing the kernel debugger I/O API to require all polling character
routines to exit immediately if there is no data allows the kernel
debugger to process multiple input channels.
NO_POLL_CHAR will be the return code to the polling routine when ever
there is no character available.
CC: linux-serial@...r.kernel.org
Signed-off-by: Jason Wessel <jason.wessel@...driver.com>
---
drivers/serial/8250.c | 4 ++--
drivers/serial/amba-pl011.c | 6 +++---
include/linux/kdb.h | 1 +
include/linux/serial_core.h | 1 +
kernel/debug/debug_core.c | 2 ++
kernel/debug/gdbstub.c | 37 +++++++++++++++++++++++++++++++------
kernel/debug/kdb/kdb_debugger.c | 10 ++++++++++
7 files changed, 50 insertions(+), 11 deletions(-)
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 2b1ea3d..891e1dd 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -1891,8 +1891,8 @@ static int serial8250_get_poll_char(struct uart_port *port)
struct uart_8250_port *up = (struct uart_8250_port *)port;
unsigned char lsr = serial_inp(up, UART_LSR);
- while (!(lsr & UART_LSR_DR))
- lsr = serial_inp(up, UART_LSR);
+ if (!(lsr & UART_LSR_DR))
+ return NO_POLL_CHAR;
return serial_inp(up, UART_RX);
}
diff --git a/drivers/serial/amba-pl011.c b/drivers/serial/amba-pl011.c
index 743ebf5..eb4cb48 100644
--- a/drivers/serial/amba-pl011.c
+++ b/drivers/serial/amba-pl011.c
@@ -342,9 +342,9 @@ static int pl010_get_poll_char(struct uart_port *port)
struct uart_amba_port *uap = (struct uart_amba_port *)port;
unsigned int status;
- do {
- status = readw(uap->port.membase + UART01x_FR);
- } while (status & UART01x_FR_RXFE);
+ status = readw(uap->port.membase + UART01x_FR);
+ if (status & UART01x_FR_RXFE)
+ return NO_POLL_CHAR;
return readw(uap->port.membase + UART01x_DR);
}
diff --git a/include/linux/kdb.h b/include/linux/kdb.h
index 4d93790..d72fa39 100644
--- a/include/linux/kdb.h
+++ b/include/linux/kdb.h
@@ -19,6 +19,7 @@
#include <asm/atomic.h>
#define KDB_POLL_FUNC_MAX 5
+extern int kdb_poll_idx;
/*
* kdb_initial_cpu is initialized to -1, and is set to the cpu
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 78dd1e7..ad83996 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -246,6 +246,7 @@ struct uart_ops {
#endif
};
+#define NO_POLL_CHAR 0x00ff0000
#define UART_CONFIG_TYPE (1 << 0)
#define UART_CONFIG_IRQ (1 << 1)
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 6e1fa82..1d71df6 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -882,6 +882,8 @@ EXPORT_SYMBOL_GPL(kgdb_unregister_io_module);
int dbg_io_get_char(void)
{
int ret = dbg_io_ops->read_char();
+ if (ret == NO_POLL_CHAR)
+ return -1;
if (!dbg_kdb_mode)
return ret;
if (ret == 127)
diff --git a/kernel/debug/gdbstub.c b/kernel/debug/gdbstub.c
index 188203a..3c00049 100644
--- a/kernel/debug/gdbstub.c
+++ b/kernel/debug/gdbstub.c
@@ -30,6 +30,7 @@
#include <linux/kernel.h>
#include <linux/kgdb.h>
+#include <linux/kdb.h>
#include <linux/reboot.h>
#include <linux/uaccess.h>
#include <asm/cacheflush.h>
@@ -62,6 +63,30 @@ static int hex(char ch)
return -1;
}
+#ifdef CONFIG_KGDB_KDB
+static int gdbstub_read_wait(void)
+{
+ int ret = -1;
+ int i;
+
+ /* poll any additional I/O interfaces that are defined */
+ while (ret < 0)
+ for (i = 0; kdb_poll_funcs[i] != NULL; i++) {
+ ret = kdb_poll_funcs[i]();
+ if (ret > 0)
+ break;
+ }
+ return ret;
+}
+#else
+static int gdbstub_read_wait(void)
+{
+ int ret = dbg_io_ops->read_char();
+ while (ret == NO_POLL_CHAR)
+ ret = dbg_io_ops->read_char();
+ return ret;
+}
+#endif
/* scan for the sequence $<data>#<checksum> */
static void get_packet(char *buffer)
{
@@ -75,7 +100,7 @@ static void get_packet(char *buffer)
* Spin and wait around for the start character, ignore all
* other characters:
*/
- while ((ch = (dbg_io_ops->read_char())) != '$')
+ while ((ch = (gdbstub_read_wait())) != '$')
/* nothing */;
kgdb_connected = 1;
@@ -88,7 +113,7 @@ static void get_packet(char *buffer)
* now, read until a # or end of buffer is found:
*/
while (count < (BUFMAX - 1)) {
- ch = dbg_io_ops->read_char();
+ ch = gdbstub_read_wait();
if (ch == '#')
break;
checksum = checksum + ch;
@@ -98,8 +123,8 @@ static void get_packet(char *buffer)
buffer[count] = 0;
if (ch == '#') {
- xmitcsum = hex(dbg_io_ops->read_char()) << 4;
- xmitcsum += hex(dbg_io_ops->read_char());
+ xmitcsum = hex(gdbstub_read_wait()) << 4;
+ xmitcsum += hex(gdbstub_read_wait());
if (checksum != xmitcsum)
/* failed checksum */
@@ -144,10 +169,10 @@ static void put_packet(char *buffer)
dbg_io_ops->flush();
/* Now see what we get in reply. */
- ch = dbg_io_ops->read_char();
+ ch = gdbstub_read_wait();
if (ch == 3)
- ch = dbg_io_ops->read_char();
+ ch = gdbstub_read_wait();
/* If we get an ACK, we are done. */
if (ch == '+')
diff --git a/kernel/debug/kdb/kdb_debugger.c b/kernel/debug/kdb/kdb_debugger.c
index f024c0c..bf6e827 100644
--- a/kernel/debug/kdb/kdb_debugger.c
+++ b/kernel/debug/kdb/kdb_debugger.c
@@ -20,7 +20,15 @@
get_char_func kdb_poll_funcs[] = {
dbg_io_get_char,
NULL,
+ NULL,
+ NULL,
+ NULL,
+ NULL,
};
+EXPORT_SYMBOL_GPL(kdb_poll_funcs);
+
+int kdb_poll_idx = 1;
+EXPORT_SYMBOL_GPL(kdb_poll_idx);
int kdb_stub(struct kgdb_state *ks)
{
@@ -85,6 +93,7 @@ int kdb_stub(struct kgdb_state *ks)
kdb_bp_remove();
KDB_STATE_CLEAR(DOING_SS);
KDB_STATE_CLEAR(DOING_SSB);
+ KDB_STATE_SET(PAGER);
/* zero out any offline cpu data */
for_each_present_cpu(i) {
if (!cpu_online(i)) {
@@ -112,6 +121,7 @@ int kdb_stub(struct kgdb_state *ks)
kdb_initial_cpu = -1;
kdb_current_task = NULL;
kdb_current_regs = NULL;
+ KDB_STATE_CLEAR(PAGER);
kdbnearsym_cleanup();
if (error == KDB_CMD_KGDB) {
if (KDB_STATE(DOING_KGDB) || KDB_STATE(DOING_KGDB2)) {
--
1.6.3.3
--
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