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authorDaniel Thompson <daniel.thompson@linaro.org>2019-10-25 10:33:27 +0300
committerDaniel Thompson <daniel.thompson@linaro.org>2019-10-28 15:08:10 +0300
commitcdca8d8900dd33ce6b8b526e247d2a6009d05de0 (patch)
tree7933f560d51b2db626038fe5d85725657e272d58 /kernel/debug
parent4f27e824bf83dfc2f6dc1a54fae419be7cd335af (diff)
downloadlinux-cdca8d8900dd33ce6b8b526e247d2a6009d05de0.tar.xz
kdb: Improve handling of characters from different input sources
Currently if an escape timer is interrupted by a character from a different input source then the new character is discarded and the function returns '\e' (which will be discarded by the level above). It is hard to see why this would ever be the desired behaviour. Fix this to return the new character rather than the '\e'. This is a bigger refactor than might be expected because the new character needs to go through escape sequence detection. Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Reviewed-by: Douglas Anderson <dianders@chromium.org> Link: https://lore.kernel.org/r/20191025073328.643-5-daniel.thompson@linaro.org
Diffstat (limited to 'kernel/debug')
-rw-r--r--kernel/debug/kdb/kdb_io.c38
1 files changed, 19 insertions, 19 deletions
diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
index 9b6933d585b5..f794c0ca4557 100644
--- a/kernel/debug/kdb/kdb_io.c
+++ b/kernel/debug/kdb/kdb_io.c
@@ -127,10 +127,10 @@ char kdb_getchar(void)
{
#define ESCAPE_UDELAY 1000
#define ESCAPE_DELAY (2*1000000/ESCAPE_UDELAY) /* 2 seconds worth of udelays */
- char escape_data[5]; /* longest vt100 escape sequence is 4 bytes */
- char *ped = escape_data;
+ char buf[4]; /* longest vt100 escape sequence is 4 bytes */
+ char *pbuf = buf;
int escape_delay = 0;
- get_char_func *f, *f_escape = NULL;
+ get_char_func *f, *f_prev = NULL;
int key;
for (f = &kdb_poll_funcs[0]; ; ++f) {
@@ -150,26 +150,26 @@ char kdb_getchar(void)
continue;
}
- if (escape_delay == 0 && key == '\e') {
+ /*
+ * When the first character is received (or we get a change
+ * input source) we set ourselves up to handle an escape
+ * sequences (just in case).
+ */
+ if (f_prev != f) {
+ f_prev = f;
+ pbuf = buf;
escape_delay = ESCAPE_DELAY;
- ped = escape_data;
- f_escape = f;
- }
- if (escape_delay) {
- if (f_escape != f)
- return '\e';
-
- *ped++ = key;
- key = kdb_handle_escape(escape_data, ped - escape_data);
- if (key < 0)
- return '\e';
- if (key == 0)
- continue;
}
- break; /* A key to process */
+ *pbuf++ = key;
+ key = kdb_handle_escape(buf, pbuf - buf);
+ if (key < 0) /* no escape sequence; return first character */
+ return buf[0];
+ if (key > 0)
+ return key;
}
- return key;
+
+ unreachable();
}
/*