[PATCH v5 3/4] kdb: Simplify kdb_defcmd macro logic

From: Sumit Garg
Date: Mon Jul 12 2021 - 09:47:00 EST


Switch to use a linked list instead of dynamic array which makes
allocation of kdb macro and traversing the kdb macro commands list
simpler.

Suggested-by: Daniel Thompson <daniel.thompson@xxxxxxxxxx>
Signed-off-by: Sumit Garg <sumit.garg@xxxxxxxxxx>
Reviewed-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
---
kernel/debug/kdb/kdb_main.c | 107 +++++++++++++++++++-----------------
1 file changed, 58 insertions(+), 49 deletions(-)

diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index b2880fad26d4..7c7a2ef834fc 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -654,13 +654,16 @@ static void kdb_cmderror(int diag)
* zero for success, a kdb diagnostic if error
*/
struct kdb_macro {
- int count;
- bool usable;
- kdbtab_t cmd;
- char **command;
+ kdbtab_t cmd; /* Macro command */
+ struct list_head statements; /* Associated statement list */
};
+
+struct kdb_macro_statement {
+ char *statement; /* Statement text */
+ struct list_head list_node; /* Statement list node */
+};
+
static struct kdb_macro *kdb_macro;
-static int kdb_macro_count;
static bool defcmd_in_progress;

/* Forward references */
@@ -668,34 +671,33 @@ static int kdb_exec_defcmd(int argc, const char **argv);

static int kdb_defcmd2(const char *cmdstr, const char *argv0)
{
- struct kdb_macro *s = kdb_macro + kdb_macro_count - 1;
- char **save_command = s->command;
+ struct kdb_macro_statement *kms;
+
+ if (!kdb_macro)
+ return KDB_NOTIMP;
+
if (strcmp(argv0, "endefcmd") == 0) {
defcmd_in_progress = false;
- if (!s->count)
- s->usable = false;
- if (s->usable)
- kdb_register(&s->cmd);
+ if (!list_empty(&kdb_macro->statements))
+ kdb_register(&kdb_macro->cmd);
return 0;
}
- if (!s->usable)
- return KDB_NOTIMP;
- s->command = kcalloc(s->count + 1, sizeof(*(s->command)), GFP_KDB);
- if (!s->command) {
- kdb_printf("Could not allocate new kdb_defcmd table for %s\n",
+
+ kms = kmalloc(sizeof(*kms), GFP_KDB);
+ if (!kms) {
+ kdb_printf("Could not allocate new kdb macro command: %s\n",
cmdstr);
- s->usable = false;
return KDB_NOTIMP;
}
- memcpy(s->command, save_command, s->count * sizeof(*(s->command)));
- s->command[s->count++] = kdb_strdup(cmdstr, GFP_KDB);
- kfree(save_command);
+
+ kms->statement = kdb_strdup(cmdstr, GFP_KDB);
+ list_add_tail(&kms->list_node, &kdb_macro->statements);
+
return 0;
}

static int kdb_defcmd(int argc, const char **argv)
{
- struct kdb_macro *save_kdb_macro = kdb_macro, *s;
kdbtab_t *mp;

if (defcmd_in_progress) {
@@ -704,13 +706,21 @@ static int kdb_defcmd(int argc, const char **argv)
kdb_defcmd2("endefcmd", "endefcmd");
}
if (argc == 0) {
- int i;
- for (s = kdb_macro; s < kdb_macro + kdb_macro_count; ++s) {
- kdb_printf("defcmd %s \"%s\" \"%s\"\n", s->cmd.cmd_name,
- s->cmd.cmd_usage, s->cmd.cmd_help);
- for (i = 0; i < s->count; ++i)
- kdb_printf("%s", s->command[i]);
- kdb_printf("endefcmd\n");
+ kdbtab_t *kp;
+ struct kdb_macro *kmp;
+ struct kdb_macro_statement *kms;
+
+ list_for_each_entry(kp, &kdb_cmds_head, list_node) {
+ if (kp->cmd_func == kdb_exec_defcmd) {
+ kdb_printf("defcmd %s \"%s\" \"%s\"\n",
+ kp->cmd_name, kp->cmd_usage,
+ kp->cmd_help);
+ kmp = container_of(kp, struct kdb_macro, cmd);
+ list_for_each_entry(kms, &kmp->statements,
+ list_node)
+ kdb_printf("%s", kms->statement);
+ kdb_printf("endefcmd\n");
+ }
}
return 0;
}
@@ -720,17 +730,11 @@ static int kdb_defcmd(int argc, const char **argv)
kdb_printf("Command only available during kdb_init()\n");
return KDB_NOTIMP;
}
- kdb_macro = kmalloc_array(kdb_macro_count + 1, sizeof(*kdb_macro),
- GFP_KDB);
+ kdb_macro = kzalloc(sizeof(*kdb_macro), GFP_KDB);
if (!kdb_macro)
goto fail_defcmd;
- memcpy(kdb_macro, save_kdb_macro,
- kdb_macro_count * sizeof(*kdb_macro));
- s = kdb_macro + kdb_macro_count;
- memset(s, 0, sizeof(*s));
- s->usable = true;

- mp = &s->cmd;
+ mp = &kdb_macro->cmd;
mp->cmd_func = kdb_exec_defcmd;
mp->cmd_minlen = 0;
mp->cmd_flags = KDB_ENABLE_ALWAYS_SAFE;
@@ -751,9 +755,9 @@ static int kdb_defcmd(int argc, const char **argv)
strcpy(mp->cmd_help, argv[3]+1);
mp->cmd_help[strlen(mp->cmd_help)-1] = '\0';
}
- ++kdb_macro_count;
+
+ INIT_LIST_HEAD(&kdb_macro->statements);
defcmd_in_progress = true;
- kfree(save_kdb_macro);
return 0;
fail_help:
kfree(mp->cmd_usage);
@@ -763,7 +767,6 @@ static int kdb_defcmd(int argc, const char **argv)
kfree(kdb_macro);
fail_defcmd:
kdb_printf("Could not allocate new kdb_macro entry for %s\n", argv[1]);
- kdb_macro = save_kdb_macro;
return KDB_NOTIMP;
}

@@ -778,25 +781,31 @@ static int kdb_defcmd(int argc, const char **argv)
*/
static int kdb_exec_defcmd(int argc, const char **argv)
{
- int i, ret;
- struct kdb_macro *s;
+ int ret;
+ kdbtab_t *kp;
+ struct kdb_macro *kmp;
+ struct kdb_macro_statement *kms;
+
if (argc != 0)
return KDB_ARGCOUNT;
- for (s = kdb_macro, i = 0; i < kdb_macro_count; ++i, ++s) {
- if (strcmp(s->cmd.cmd_name, argv[0]) == 0)
+
+ list_for_each_entry(kp, &kdb_cmds_head, list_node) {
+ if (strcmp(kp->cmd_name, argv[0]) == 0)
break;
}
- if (i == kdb_macro_count) {
+ if (list_entry_is_head(kp, &kdb_cmds_head, list_node)) {
kdb_printf("kdb_exec_defcmd: could not find commands for %s\n",
argv[0]);
return KDB_NOTIMP;
}
- for (i = 0; i < s->count; ++i) {
- /* Recursive use of kdb_parse, do not use argv after
- * this point */
+ kmp = container_of(kp, struct kdb_macro, cmd);
+ list_for_each_entry(kms, &kmp->statements, list_node) {
+ /*
+ * Recursive use of kdb_parse, do not use argv after this point.
+ */
argv = NULL;
- kdb_printf("[%s]kdb> %s\n", s->cmd.cmd_name, s->command[i]);
- ret = kdb_parse(s->command[i]);
+ kdb_printf("[%s]kdb> %s\n", kmp->cmd.cmd_name, kms->statement);
+ ret = kdb_parse(kms->statement);
if (ret)
return ret;
}
--
2.25.1