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@vger.kernel.org
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>

diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 2b1ea3d4c4f41e4b444c0541ce9285703f5f28fc..891e1dd65f244ef20b2cc4f75ba980c939d3078f 100644 (file)
--- 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 743ebf5f16da8942bc6c7d23508cc69cfd9eb229..eb4cb480b93e9be344f9f84bbd574c68fe3ec8e6 100644 (file)
--- 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 4d93790faec3c06f7ec5591445cf2d73e143ea4e..d72fa3908128a1adba3ab21d5cec998d0fc4586b 100644 (file)
--- 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 78dd1e7120a98bec0960f5aa63d3f499f3b2e336..ad839963fa684c9bce711ba570225b587cf6b319 100644 (file)
--- 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 6e1fa829fdebd5d0bf9ed1f849ba99239d74ce82..1d71df66f3fa7c9027e39742e4fc0680acdde1b6 100644 (file)
--- 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 188203a1965788abc495c98f6ac1cc28e3d7acad..3c000490a7dd1938cb20a3f410ab31223bbf8c18 100644 (file)
--- 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 f024c0c4b8c423999286c8a2c59f167533a8c795..bf6e8270e95781469d07c08652cab9edd7c45d71 100644 (file)
--- 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)) {