Commit 64d504cf authored by Daniel Thompson's avatar Daniel Thompson
Browse files

kdb: Simplify management of tmpbuffer in kdb_read() 



The current approach to filling tmpbuffer with completion candidates is
confusing, with the buffer management being especially hard to reason
about. That's because it doesn't copy the completion canidate into
tmpbuffer, instead of copies a whole bunch of other nonsense and then
runs the completion search from the middle of tmpbuffer!

Change this to copy nothing but the completion candidate into tmpbuffer.

Pretty much everything else in this patch is renaming to reflect the
above change:

    s/p_tmp/tmpbuffer/
    s/buf_size/sizeof(tmpbuffer)/

Reviewed-by: default avatarDouglas Anderson <dianders@chromium.org>
Tested-by: default avatarJustin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20240424-kgdb_read_refactor-v3-7-f236dbe9828d@linaro.org


Signed-off-by: default avatarDaniel Thompson <daniel.thompson@linaro.org>
parent 80bd73c1

kernel/debug/kdb/kdb_io.c

+18 −23
Original line number Diff line number Diff line
@@ -239,6 +239,7 @@ static char *kdb_read(char *buffer, size_t bufsize) 
						 * and null byte */

	char *lastchar;

	char *p_tmp;

	char tmp;

	static char tmpbuffer[CMD_BUFLEN];

	int len = strlen(buffer);

	int len_tmp;
@@ -246,8 +247,7 @@ static char *kdb_read(char *buffer, size_t bufsize) 
	int count;

	int i;

	int diag, dtab_count;

	int key, buf_size, ret;



	int key, ret;



	diag = kdbgetintenv("DTABCOUNT", &dtab_count);

	if (diag)
@@ -329,21 +329,16 @@ static char *kdb_read(char *buffer, size_t bufsize) 
	case 9: /* Tab */

		if (tab < 2)

			++tab;

		p_tmp = buffer;

		while (*p_tmp == ' ')

			p_tmp++;

		if (p_tmp > cp)

			break;

		memcpy(tmpbuffer, p_tmp, cp-p_tmp);

		*(tmpbuffer + (cp-p_tmp)) = '\0';

		p_tmp = strrchr(tmpbuffer, ' ');

		if (p_tmp)

			++p_tmp;

		else

			p_tmp = tmpbuffer;

		len = strlen(p_tmp);

		buf_size = sizeof(tmpbuffer) - (p_tmp - tmpbuffer);

		count = kallsyms_symbol_complete(p_tmp, buf_size);



		tmp = *cp;

		*cp = '\0';

		p_tmp = strrchr(buffer, ' ');

		p_tmp = (p_tmp ? p_tmp + 1 : buffer);

		strscpy(tmpbuffer, p_tmp, sizeof(tmpbuffer));

		*cp = tmp;



		len = strlen(tmpbuffer);

		count = kallsyms_symbol_complete(tmpbuffer, sizeof(tmpbuffer));

		if (tab == 2 && count > 0) {

			kdb_printf("\n%d symbols are found.", count);

			if (count > dtab_count) {
@@ -355,14 +350,14 @@ static char *kdb_read(char *buffer, size_t bufsize) 
			}

			kdb_printf("\n");

			for (i = 0; i < count; i++) {

				ret = kallsyms_symbol_next(p_tmp, i, buf_size);

				ret = kallsyms_symbol_next(tmpbuffer, i, sizeof(tmpbuffer));

				if (WARN_ON(!ret))

					break;

				if (ret != -E2BIG)

					kdb_printf("%s ", p_tmp);

					kdb_printf("%s ", tmpbuffer);

				else

					kdb_printf("%s... ", p_tmp);

				*(p_tmp + len) = '\0';

					kdb_printf("%s... ", tmpbuffer);

				tmpbuffer[len] = '\0';

			}

			if (i >= dtab_count)

				kdb_printf("...");
@@ -373,14 +368,14 @@ static char *kdb_read(char *buffer, size_t bufsize) 
				kdb_position_cursor(kdb_prompt_str, buffer, cp);

		} else if (tab != 2 && count > 0) {

			/* How many new characters do we want from tmpbuffer? */

			len_tmp = strlen(p_tmp) - len;

			len_tmp = strlen(tmpbuffer) - len;

			if (lastchar + len_tmp >= bufend)

				len_tmp = bufend - lastchar;



			if (len_tmp) {

				/* + 1 ensures the '\0' is memmove'd */

				memmove(cp+len_tmp, cp, (lastchar-cp) + 1);

				memcpy(cp, p_tmp+len, len_tmp);

				memcpy(cp, tmpbuffer+len, len_tmp);

				kdb_printf("%s", cp);

				cp += len_tmp;

				lastchar += len_tmp;