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    Subject[PATCH 19/25] dynamic_debug: add flags filtering to flags spec
    Date
    Change definition of flags spec to [pmflta_]*[-+=][pmflta_]*
    The flags preceding the op are optional filter-flags; if provided,
    they add an additional constraint to call-site matching done
    by ddebug_change; call-sites which do not have all specified flags
    are skipped (additional flags are allowed).

    This allows query/rules like "p+t" to turn on TID logging for all
    currently enabled call-sites, while leaving the others alone.
    This will also allow filtering on pending rules (with 'a' flag),
    which will support removal of pending rules.

    Also allow 0 flags byte, so that active rules can be completely
    reset by writing "p=" or "p=_".

    Patch factors flag-scanning into ddebug_parse_flag_settings(),
    and uses it for both filter-flags and new flags, and adds pr_err()
    where useful.

    Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
    ---
    lib/dynamic_debug.c | 81 ++++++++++++++++++++++++++++++++-------------------
    1 files changed, 51 insertions(+), 30 deletions(-)

    diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
    index 37f9748..275cf30 100644
    --- a/lib/dynamic_debug.c
    +++ b/lib/dynamic_debug.c
    @@ -180,7 +180,8 @@ static bool query_matches_callsite(struct _ddebug *dp,
    * were matched. Called with ddebug_lock held.
    */
    static int ddebug_change(const struct ddebug_query *query,
    - unsigned int flags, unsigned int mask)
    + unsigned int flags, unsigned int mask,
    + unsigned int filter)
    {
    int i;
    struct ddebug_table *dt;
    @@ -202,6 +203,9 @@ static int ddebug_change(const struct ddebug_query *query,
    if (!query_matches_callsite(dp, query))
    continue;

    + if (filter && (dp->flags & filter) != filter)
    + continue;
    +
    nfound++;

    newflags = (dp->flags & mask) | flags;
    @@ -402,28 +406,9 @@ static int ddebug_parse_query(char *words[], int nwords,
    return 0;
    }

    -/*
    - * Parse `str' as a flags specification, format [-+=][p]+.
    - * Sets up *maskp and *flagsp to be used when changing the
    - * flags fields of matched _ddebug's. Returns 0 on success
    - * or <0 on error.
    - */
    -static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
    - unsigned int *maskp)
    +static int ddebug_parse_flag_settings(const char *str)
    {
    - unsigned flags = 0;
    - int op = '=', i;
    -
    - switch (*str) {
    - case '+':
    - case '-':
    - case '=':
    - op = *str++;
    - break;
    - default:
    - return -EINVAL;
    - }
    - pr_debug("op='%c'\n", op);
    + int i, flags = 0;

    for ( ; *str ; ++str) {
    for (i = ARRAY_SIZE(opt_array) - 1; i >= 0; i--) {
    @@ -432,12 +417,46 @@ static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
    break;
    }
    }
    - if (i < 0)
    + if (i < 0 && *str) {
    + pr_err("unknown flag: %c\n", *str);
    return -EINVAL;
    + }
    }
    - if (flags == 0)
    + return flags;
    +}
    +
    +/*
    + * Parse `str' as a flags filter and specification, with format
    + * [ptlmfa]*[-+=][ptlmfa]+. Sets up *maskp, *flagsp and *filterp to
    + * be used when changing the flags fields of matched _ddebug's.
    + * Returns 0 on success or <0 on error.
    + */
    +static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
    + unsigned int *maskp, unsigned int *filterp)
    +{
    + int flags, filter;
    + int op = '=';
    + char *s = strpbrk(str, "+-=");
    +
    + if (!s) {
    + pr_err("flags spec missing op, expecting [+-=]\n");
    return -EINVAL;
    - pr_debug("flags=0x%x\n", flags);
    + } else {
    + op = *s;
    + *s++ = '\0';
    + }
    + filter = ddebug_parse_flag_settings(str);
    + if (filter < 0) {
    + pr_err("flags_filter=0x%x\n", filter);
    + return -EINVAL;
    + }
    + *filterp = filter;
    +
    + flags = ddebug_parse_flag_settings(s);
    + if (flags < 0) {
    + pr_err("flags=0x%x\n", flags);
    + return -EINVAL;
    + }

    /* calculate final *flagsp, *maskp according to mask and op */
    switch (op) {
    @@ -454,7 +473,9 @@ static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
    *flagsp = 0;
    break;
    }
    - pr_debug("*flagsp=0x%x *maskp=0x%x\n", *flagsp, *maskp);
    + pr_debug("filter=0x%x op='%c' flags=0x%x *flagsp=0x%x *maskp=0x%x\n",
    + filter, op, flags, *flagsp, *maskp);
    +
    return 0;
    }

    @@ -539,7 +560,7 @@ static int ddebug_save_pending(struct ddebug_query *query,

    static int ddebug_exec_query(char *query_string)
    {
    - unsigned int flags = 0, mask = 0;
    + unsigned int flags = 0, mask = 0, filter = 0;
    struct ddebug_query query;
    #define MAXWORDS 9
    int nwords;
    @@ -551,12 +572,12 @@ static int ddebug_exec_query(char *query_string)
    return -EINVAL;
    if (ddebug_parse_query(words, nwords-1, &query))
    return -EINVAL;
    - if (ddebug_parse_flags(words[nwords-1], &flags, &mask))
    + if (ddebug_parse_flags(words[nwords-1], &flags, &mask, &filter))
    return -EINVAL;

    /* actually go and implement the change */
    mutex_lock(&ddebug_lock);
    - nfound = ddebug_change(&query, flags, mask);
    + nfound = ddebug_change(&query, flags, mask, filter);
    qstr = show_ddebug_query(&query);
    pr_debug("nfound %d on %s\n", nfound, qstr);
    if (!nfound) {
    @@ -917,7 +938,7 @@ static void apply_pending_queries(struct ddebug_table *dt)
    char *qstr;

    list_for_each_entry_safe(pq, pqnext, &pending_queries, link) {
    - nfound = ddebug_change(&pq->query, pq->flags, pq->mask);
    + nfound = ddebug_change(&pq->query, pq->flags, pq->mask, 0);
    qstr = show_pending_query(pq);
    pr_debug("%s: %s\n", (nfound) ? "applied" : "no-match", qstr);
    kfree(qstr);
    --
    1.7.4.1


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