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    Subject[PATCH 20/25] dynamic_debug: rename ddebug param to dyndbg, plus minor tweaks
    Date
    From: Jim Cromie <jim.cromie@gmail.com>

    user-visible:
    - change param-name from "ddebug" to "dyndbg". This is more clearly
    associated with dynamic-debug, and more distinct from other *debug*
    names.

    minor internal tweaks:
    - drop return 0 in the inline void ddebug_module_parse_args stub,
    in #ifndef CONFIG_DYNAMIC_DEBUG case, to silence warning.
    - make ddebug_exec_query static again, its not used elsewhere.
    - shrink stack in ddebug_boot_parse_args, move auto vars to __initdata.
    - convert printk()s to pr_info()s.
    - add "mod" prefix to ddebug_module_parse_args(name, args, ...) parameters.
    - in ddebug_module_parse_args(), return early if no mod-params,
    to avoid non-pertinent pr_info()s and kstrdup.
    - in ddebug_module_parse_args() and ddebug_boot_parse_args() arg scan
    loops, invert param-name == "ddebug" checks and continue. This
    avoids pr_info()s for uninteresting args, and reduces indenting.
    - use ddebug_exec_queries() instead of ddebug_exec_query().

    Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
    CC: Thomas Renninger <trenn@suse.de>
    CC: Rusty Russell <rusty@rustcorp.com.au>
    ---
    Documentation/dynamic-debug-howto.txt | 57 +++++++++++++++++++--------
    include/linux/dynamic_debug.h | 7 +---
    kernel/params.c | 8 ++--
    lib/dynamic_debug.c | 67 +++++++++++++++++----------------
    4 files changed, 79 insertions(+), 60 deletions(-)

    diff --git a/Documentation/dynamic-debug-howto.txt b/Documentation/dynamic-debug-howto.txt
    index 269065d..8363a56 100644
    --- a/Documentation/dynamic-debug-howto.txt
    +++ b/Documentation/dynamic-debug-howto.txt
    @@ -241,28 +241,40 @@ this boot parameter for debugging purposes.
    Debug Messages at Module Initialization Time
    ============================================

    -Enabling debug messages inside a module is only possible if the module itself
    -is loaded already. If you unload a module, the dynamic debug flags associated
    -to its debug messages are lost.
    -Therefore, enabling debug messages that get processed at module initialization
    -time through the <debugfs>/dynamic_debug/control interface is not possible.
    -Instead, a "ddebug" module paramter can be passed:
    +Enabling a module's debug messages via debug control file only works
    +once the module is loaded; too late for callsites in init functions.
    +And when module is unloaded, debug flag settings for the module are
    +lost. Instead, a "dyndbg" module parameter can be passed:

    - - via kernel boot parameter:
    - module.ddebug
    + - via kernel boot parameter: (this form works on built-ins too)
    + module.dyndbg=+mfp
    + module.dyndbg # defaults to +p

    - - as an ordinary module parameter via modprobe
    - modprobe module ddebug
    + - as an ordinary module parameter via modprobe modprobe module
    + $> modprobe module dyndbg +pmfl # defaults to +p

    - or the parameter can be used permanently via modprobe.conf(.local)
    - options module ddebug
    + options module dyndbg=+pmflt
    + options module dyndbg # defaults to +p

    -The ddebug option is not implemented as an ordinary module parameter and thus
    -will not show up in /sys/module/module_name/parameters/ddebug
    -The settings can get reverted through the sysfs interface again when the
    -module got loaded as soon as debug messages are not needed anymore:
    -echo "module module_name -p" > <debugfs>/dynamic_debug/control
    -as described in the "Command Language Reference" chapter above.
    +The $modname.dyndbg="value" should exclude "module $modname", as the
    +$modname is taken from the param-name, and only 1 spec of each type is
    +allowed.
    +
    +The ddebug option is not implemented as an ordinary module parameter
    +and thus will not show up in /sys/module/module_name/parameters/ddebug
    +The settings can be reverted later via the sysfs interface if the
    +debug messages are no longer needed:
    +
    + echo "module module_name -p" > <debugfs>/dynamic_debug/control
    +
    +$module.dyndbg="..." on boot-line works on built-in modules as well as
    +those loaded by modprobe (from either early or normal userspace), and
    +somewhat overlaps debug_query functionality.
    +
    +Modprobed modules get ddebug flags given on boot-line after those
    +given via modprobe (either explicitly, or from /etc/modprobe.d/*).
    +This can surprise if boot-line arg subtracts flags.

    Examples
    ========
    @@ -290,3 +302,14 @@ nullarbor:~ # echo -n 'func svc_process -p' >
    // enable messages for NFS calls READ, READLINK, READDIR and READDIR+.
    nullarbor:~ # echo -n 'format "nfsd: READ" +p' >
    <debugfs>/dynamic_debug/control
    +
    +// boot-args example, with newlines and comments
    +Kernel command line: ...
    + ddebug_query="func i2c_del_adapter +p; func tboot_probe +p"
    + dynamic_debug.verbose=1 // see whats going on
    + nouveau.dyndbg // implicit =+p
    + tsc_sync.dyndbg=+p // builtin on my kernel
    + i2c_core.dyndbg=+p // loaded by udev
    + *.dyndbg="=_" // wildcard applies to builtins
    + k10temp.dyndbg="+p # comment in query is stripped "
    + pnp.dyndbg="func pnpacpi_get_resources +p; func pnp_assign_mem +p" # multi
    diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
    index d6f5b5c..29b57e5 100644
    --- a/include/linux/dynamic_debug.h
    +++ b/include/linux/dynamic_debug.h
    @@ -47,7 +47,6 @@ extern int ddebug_remove_module(const char *mod_name);
    extern __printf(2, 3)
    int __dynamic_pr_debug(struct _ddebug *descriptor, const char *fmt, ...);

    -extern int ddebug_exec_query(char *query_string);
    extern void ddebug_module_parse_args(const char *name, char* args,
    struct kernel_param *params, unsigned num);

    @@ -105,15 +104,11 @@ static inline int ddebug_remove_module(const char *mod)
    {
    return 0;
    }
    -static inline int ddebug_exec_query(char *query_string)
    -{
    - return 0;
    -}
    +
    static inline void ddebug_module_parse_args(const char *name, char* args,
    struct kernel_param *params,
    unsigned num)
    {
    - return 0;
    }

    #define dynamic_pr_debug(fmt, ...) \
    diff --git a/kernel/params.c b/kernel/params.c
    index 313ea84..010f167 100644
    --- a/kernel/params.c
    +++ b/kernel/params.c
    @@ -116,12 +116,12 @@ static int parse_one(char *param,
    }

    /*
    - * Ignore ddebug module params and module.ddebug boot params:
    + * Ignore ddebug module params and module.dyndbg boot params:
    * Documentation/dynamic-debug-howto.txt
    */
    - tmp = strstr(param, ".ddebug");
    - if (parameq(param, "ddebug") || (tmp && strlen(tmp) == 7)) {
    - DEBUGP("Ignoring ddebug parameter %s\n", param);
    + tmp = strstr(param, ".dyndbg");
    + if (parameq(param, "dyndbg") || (tmp && strlen(tmp) == 7)) {
    + pr_debug("Ignoring ddebug parameter %s\n", param);
    return 0;
    }

    diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
    index bb66251..afc9bd3 100644
    --- a/lib/dynamic_debug.c
    +++ b/lib/dynamic_debug.c
    @@ -449,7 +449,7 @@ static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
    return 0;
    }

    -int ddebug_exec_query(char *query_string)
    +static int ddebug_exec_query(char *query_string)
    {
    unsigned int flags = 0, mask = 0;
    struct ddebug_query query;
    @@ -458,7 +458,7 @@ int ddebug_exec_query(char *query_string)
    char *words[MAXWORDS];

    if (verbose)
    - printk(KERN_INFO "%s: got query: %s\n", __func__, query_string);
    + pr_info("got query: %s\n", query_string);

    nwords = ddebug_tokenize(query_string, words, MAXWORDS);
    if (nwords <= 0)
    @@ -879,53 +879,55 @@ int ddebug_add_module(struct _ddebug *tab, unsigned int n,
    EXPORT_SYMBOL_GPL(ddebug_add_module);

    /* We search for *ddebug* module params */
    -void ddebug_module_parse_args(const char *name, char* args,
    +void ddebug_module_parse_args(const char *modname, char* modargs,
    struct kernel_param *params, unsigned num)
    {
    char ddebug[DDEBUG_STRING_SIZE], *param, *val, *args_it, *arg_dup_ptr;
    int i;

    + if (!modargs || !*modargs)
    + return; /* no args, return now, avoid pr_infos */
    /*
    * We must not modify the passed args string and need to store the
    * kstrdup pointer to be able to free memory later, TBD: find a way
    * to do this nicer
    */
    - arg_dup_ptr = args_it = kstrdup(args, GFP_KERNEL);
    + arg_dup_ptr = args_it = kstrdup(modargs, GFP_KERNEL);
    + args_it = skip_spaces(args_it);

    if (verbose)
    - printk(KERN_INFO "%s: Parsing ARGS: -%s- of %s\n",
    - __func__, args_it, name);
    + pr_info("%s ARGS: %s\n", modname, args_it);

    + /* warn if modules declare ddebug param - todo BUILD_BUG ?? */
    for (i = 0; i < num; i++) {
    if (!strcmp("ddebug", params[i].name))
    pr_warning("Module %s uses reserved keyword "
    - "*ddebug* as parameter\n", name);
    + "*ddebug* as parameter\n", modname);
    }

    - /* Chew leading spaces */
    - args_it = skip_spaces(args_it);
    -
    while (*args_it) {
    args_it = next_arg(args_it, &param, &val);
    + if (strcmp(param, "dyndbg"))
    + continue;
    + pr_info("Enabling debugging for module %s\n", modname);
    if (verbose)
    - printk(KERN_INFO "%s: Param: %s, val: %s\n",
    - __func__, param, val);
    - if (!strcmp(param, "ddebug")) {
    - pr_info("Enabling debugging for module %s\n", name);
    - snprintf(ddebug, DDEBUG_STRING_SIZE, "module %s +p",
    - name);
    - ddebug_exec_query(ddebug);
    - }
    + pr_info("Param: %s, val: %s\n", param, val);
    +
    + snprintf(ddebug, DDEBUG_STRING_SIZE, "module %s +p", modname);
    + ddebug_exec_queries(ddebug);
    }
    kfree(arg_dup_ptr);
    if (verbose)
    - printk(KERN_INFO "%s: Finished %s parsing\n", __func__, name);
    + pr_info("Finished %s parsing\n", modname);
    }
    -/* We search for module.ddebug kernel boot params */
    -static void ddebug_boot_parse_args(void)
    +
    +char __initdata tmp_cmd_arr[COMMAND_LINE_SIZE];
    +char __initdata module[MODULE_NAME_LEN], ddebug[DDEBUG_STRING_SIZE];
    +
    +/* We search for module.dyndbg kernel boot params */
    +static __init void ddebug_boot_parse_args(void)
    {
    - char tmp_cmd_arr[COMMAND_LINE_SIZE], *tmp_cmd_ptr, *param, *val, *tmp;
    - char module[MODULE_NAME_LEN], ddebug[DDEBUG_STRING_SIZE];
    + char *tmp_cmd_ptr, *param, *val, *tmp;

    /* next_arg touches the passed buffer and chops each argument */
    strlcpy(tmp_cmd_arr, saved_command_line, COMMAND_LINE_SIZE);
    @@ -934,17 +936,16 @@ static void ddebug_boot_parse_args(void)

    while (*tmp_cmd_ptr) {
    tmp_cmd_ptr = next_arg(tmp_cmd_ptr, &param, &val);
    + tmp = strstr(param, ".dyndbg");
    + if (!tmp || strlen(tmp) != 7)
    + continue;
    + strlcpy(module, param, tmp - param + 1);
    + pr_info("Enabling debugging for module %s\n", module);
    if (verbose)
    - printk(KERN_INFO "%s: Param: %s, val: %s\n",
    - __func__, param, val);
    - tmp = strstr(param, ".ddebug");
    - if (tmp && strlen(tmp) == 7) {
    - strlcpy(module, param, tmp - param + 1);
    - pr_info("Enabling debugging for module %s\n", module);
    - snprintf(ddebug, DDEBUG_STRING_SIZE, "module %s +p",
    - module);
    - ddebug_exec_query(ddebug);
    - }
    + pr_info("Param: %s, val: %s\n", param, val);
    +
    + snprintf(ddebug, DDEBUG_STRING_SIZE, "module %s +p", module);
    + ddebug_exec_queries(ddebug);
    }
    }

    --
    1.7.7.3


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