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    Subject[PATCH 09/11] dynamic_debug: add_to_pending() saves non-matching queries for later.
    Date
    When a query/rule doesnt match, call add_to_pending(new function)
    to copy the query off the stack, into a (new) struct pending_query,
    and add to pending_queries (new) list.

    Patch adds: /sys/module/dynamic_debug/parameters/
    verbose - rw, added previously, here for completeness
    pending_ct - ro, shows current count of pending queries
    pending_max - rw, set max pending, further pending queries are rejected

    With this and previous patches, queries added on the boot-line which
    do not match (because module is not built-in, and thus not present yet)
    are added to pending_queries.

    IE, with these boot-line additions:
    dynamic_debug.verbose=1 ddebug_query="module scx200_hrt +p"

    Kernel will log the following:

    ddebug_exec_queries: query 0: "module scx200_hrt +p"
    ddebug_tokenize: split into words: "module" "scx200_hrt" "+p"
    ddebug_parse_query: parsed q->function="(null)" q->filename="(null)" q->module="scx200_hrt" q->format="(null)" q->lineno=0-0
    ddebug_parse_flags: op='+'
    ddebug_parse_flags: flags=0x1
    ddebug_parse_flags: *flagsp=0x1 *maskp=0xffffffff
    ddebug_exec_query: nfound 0 on q->function="(null)" q->filename="(null)" q->module="scx200_hrt" q->format="(null)" q->lineno=0-0
    ddebug_add_to_pending: add to pending: q->function="(null)" q->filename="(null)" q->module="scx200_hrt" q->format="(null)" q->lineno=0-0
    ddebug_add_to_pending: ddebug: query saved as pending 1

    Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
    ---
    lib/dynamic_debug.c | 78 +++++++++++++++++++++++++++++++++++++++++++++++----
    1 files changed, 72 insertions(+), 6 deletions(-)

    diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
    index 9b8b1e8..37d0275 100644
    --- a/lib/dynamic_debug.c
    +++ b/lib/dynamic_debug.c
    @@ -53,6 +53,16 @@ struct ddebug_query {
    unsigned int first_lineno, last_lineno;
    };

    +struct pending_query {
    + struct list_head link;
    + struct ddebug_query query;
    + char filename[100];
    + char module[30];
    + char function[50];
    + char format[200];
    + unsigned int flags, mask;
    +};
    +
    struct ddebug_iter {
    struct ddebug_table *table;
    unsigned int idx;
    @@ -61,7 +71,13 @@ struct ddebug_iter {
    static DEFINE_MUTEX(ddebug_lock);
    static LIST_HEAD(ddebug_tables);
    static int verbose = 0;
    -module_param(verbose, int, 0744);
    +module_param(verbose, int, 0644);
    +
    +/* legal but inapplicable queries, save and test against new modules */
    +static LIST_HEAD(pending_queries);
    +static int pending_ct, pending_max = 100;
    +module_param(pending_ct, int, 0444);
    +module_param(pending_max, int, 0644);

    /* Return the last part of a pathname */
    static inline const char *basename(const char *path)
    @@ -96,6 +112,56 @@ static char *ddebug_describe_flags(struct _ddebug *dp, char *buf,
    return buf;
    }

    +static char prbuf_query[300];
    +
    +static char *show_ddebug_query(const struct ddebug_query *q)
    +{
    + sprintf(prbuf_query,
    + "q->function=\"%s\" q->filename=\"%s\" "
    + "q->module=\"%s\" q->format=\"%s\" q->lineno=%u-%u",
    + q->function, q->filename, q->module, q->format,
    + q->first_lineno, q->last_lineno);
    +
    + return prbuf_query;
    +}
    +
    +/* copy query off stack, save flags & mask, and store in pending-list */
    +static void add_to_pending(const struct ddebug_query *query,
    + unsigned int flags, unsigned int mask)
    +{
    + struct pending_query *pq;
    +
    + if (pending_ct >= pending_max) {
    + pr_warn("ddebug: no matches for query, pending is full\n");
    + return;
    + }
    + if (verbose)
    + pr_info("add to pending: %s\n", show_ddebug_query(query));
    +
    + pending_ct++;
    + pq = kzalloc(sizeof(struct pending_query), GFP_KERNEL);
    +
    + /* copy non-null match-specs into allocd mem, update pointers */
    + if (query->module)
    + pq->query.module = strcpy(pq->module, query->module);
    + if (query->function)
    + pq->query.function = strcpy(pq->function, query->function);
    + if (query->filename)
    + pq->query.filename = strcpy(pq->filename, query->filename);
    + if (query->format)
    + pq->query.format = strcpy(pq->format, query->format);
    +
    + pq->flags = flags;
    + pq->mask = mask;
    +
    + mutex_lock(&ddebug_lock);
    + list_add(&pq->link, &pending_queries);
    + mutex_unlock(&ddebug_lock);
    +
    + if (verbose)
    + pr_info("ddebug: query saved as pending %d\n", pending_ct);
    +}
    +
    /*
    * Search the tables for _ddebug's which match the given
    * `query' and apply the `flags' and `mask' to them. Tells
    @@ -348,11 +414,7 @@ static int ddebug_parse_query(char *words[], int nwords,
    }

    if (verbose)
    - pr_info("q->function=\"%s\" q->filename=\"%s\" "
    - "q->module=\"%s\" q->format=\"%s\" q->lineno=%u-%u\n",
    - query->function, query->filename,
    - query->module, query->format, query->first_lineno,
    - query->last_lineno);
    + pr_info("parsed %s\n", show_ddebug_query(query));

    return 0;
    }
    @@ -437,6 +499,10 @@ static int ddebug_exec_query(char *query_string)
    /* actually go and implement the change */
    nfound = ddebug_change(&query, flags, mask);

    + pr_info("nfound %d on %s\n", nfound, show_ddebug_query(&query));
    + if (!nfound)
    + ddebug_add_to_pending(&query, flags, mask);
    +
    return 0;
    }

    --
    1.7.4.1


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