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    Subject[PATCH 5/6] kmod: Add new call_usermodehelper_timeout() API

    In the blasphemous occasions that the Kernel must call a user-mode program
    half of the times it is more robust to not wait forever but limit the wait
    for a specified timeout.

    So add a new call_usermodehelper_timeout() that implements that.
    (Users of this new API will be added once this API is in mainline)

    call_usermodehelper_fns() is added an extra timeout parameter which
    is then implemented in call_usermodehelper_exec. The few users of
    call_usermodehelper_fns() are also changed in this patch.

    Also an gfp_t parameter is added, for finer allocation control

    The code in call_usermodehelper_exec is simplified by the use of
    the all-mighty wait_for_completion_timeout_state() which is able
    to wait in all the different modes. See:
    completion: Add wait_for_completion_timeout_state()

    Should some wait-forever callers today, be converted to this new
    schema?

    CC: Trond Myklebust <Trond.Myklebust@netapp.com>
    Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
    ---
    fs/exec.c | 4 ++--
    include/linux/kmod.h | 19 ++++++++++++++-----
    kernel/kmod.c | 24 ++++++++++++------------
    kernel/sys.c | 2 +-
    security/keys/request_key.c | 2 +-
    5 files changed, 30 insertions(+), 21 deletions(-)

    diff --git a/fs/exec.c b/fs/exec.c
    index 23559c2..8789ba8 100644
    --- a/fs/exec.c
    +++ b/fs/exec.c
    @@ -2185,8 +2185,8 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs)
    }

    retval = call_usermodehelper_fns(helper_argv[0], helper_argv,
    - NULL, UMH_WAIT_EXEC, umh_pipe_setup,
    - NULL, &cprm);
    + NULL, UMH_WAIT_EXEC, 0, 0,
    + umh_pipe_setup, NULL, &cprm);
    argv_free(helper_argv);
    if (retval) {
    printk(KERN_INFO "Core dump to %s pipe failed\n",
    diff --git a/include/linux/kmod.h b/include/linux/kmod.h
    index ae3f9623..4d9f202 100644
    --- a/include/linux/kmod.h
    +++ b/include/linux/kmod.h
    @@ -60,21 +60,30 @@ struct subprocess_info {
    char **argv;
    char **envp;
    int wait;
    + unsigned long timeout;
    int retval;
    int (*init)(struct subprocess_info *info, struct cred *new);
    void (*cleanup)(struct subprocess_info *info);
    void *data;
    };

    -extern int
    -call_usermodehelper_fns(char *path, char **argv, char **envp, int wait,
    - int (*init)(struct subprocess_info *info, struct cred *new),
    - void (*cleanup)(struct subprocess_info *), void *data);
    +extern int call_usermodehelper_fns(char *path, char **argv, char **envp,
    + int wait, unsigned long timeout, gfp_t gfp,
    + int (*init)(struct subprocess_info *info, struct cred *new),
    + void (*cleanup)(struct subprocess_info *), void *data);

    static inline int
    call_usermodehelper(char *path, char **argv, char **envp, int wait)
    {
    - return call_usermodehelper_fns(path, argv, envp, wait,
    + return call_usermodehelper_fns(path, argv, envp, wait, 0, 0,
    + NULL, NULL, NULL);
    +}
    +
    +static inline int
    +call_usermodehelper_timeout(char *path, char **argv, char **envp,
    + int wait, unsigned long timeout, gfp_t gfp)
    +{
    + return call_usermodehelper_fns(path, argv, envp, wait, timeout, gfp,
    NULL, NULL, NULL);
    }

    diff --git a/kernel/kmod.c b/kernel/kmod.c
    index b404f99..588cb6f 100644
    --- a/kernel/kmod.c
    +++ b/kernel/kmod.c
    @@ -90,7 +90,7 @@ static int call_modprobe(char *module_name, int wait)
    argv[4] = NULL;

    return call_usermodehelper_fns(modprobe_path, argv, envp,
    - wait | UMH_KILLABLE, NULL, free_modprobe_argv, NULL);
    + wait | UMH_KILLABLE, 0, 0, NULL, free_modprobe_argv, NULL);
    free_argv:
    kfree(argv);
    out:
    @@ -522,6 +522,7 @@ void call_usermodehelper_setfns(struct subprocess_info *info,
    int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
    {
    DECLARE_COMPLETION_ONSTACK(done);
    + int wait_state;
    int retval = 0;

    helper_lock();
    @@ -540,19 +541,15 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
    if (wait == UMH_NO_WAIT) /* task has freed sub_info */
    goto unlock;

    - if (wait & UMH_KILLABLE) {
    - retval = wait_for_completion_killable(&done);
    - if (!retval)
    - goto wait_done;
    -
    + wait_state = (wait & UMH_KILLABLE) ? TASK_KILLABLE : 0;
    + retval = wait_for_completion_timeout_state(&done, sub_info->timeout,
    + wait_state);
    + if (unlikely(retval)) {
    /* umh_complete() will see NULL and free sub_info */
    if (xchg(&sub_info->complete, NULL))
    goto unlock;
    - /* fallthrough, umh_complete() was already called */
    }

    - wait_for_completion(&done);
    -wait_done:
    retval = sub_info->retval;
    out:
    call_usermodehelper_freeinfo(sub_info);
    @@ -561,13 +558,15 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
    return retval;
    }

    -int call_usermodehelper_fns(
    - char *path, char **argv, char **envp, int wait,
    +int call_usermodehelper_fns(char *path, char **argv, char **envp,
    + int wait, unsigned long timeout, gfp_t gfp_mask,
    int (*init)(struct subprocess_info *info, struct cred *new),
    void (*cleanup)(struct subprocess_info *), void *data)
    {
    struct subprocess_info *info;
    - gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
    +
    + if (!gfp_mask)
    + gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;

    info = call_usermodehelper_setup(path, argv, envp, gfp_mask);

    @@ -575,6 +574,7 @@ int call_usermodehelper_fns(
    return -ENOMEM;

    call_usermodehelper_setfns(info, init, cleanup, data);
    + info->timeout = timeout;

    return call_usermodehelper_exec(info, wait);
    }
    diff --git a/kernel/sys.c b/kernel/sys.c
    index 37b1971..16d14d1 100644
    --- a/kernel/sys.c
    +++ b/kernel/sys.c
    @@ -2020,7 +2020,7 @@ int orderly_poweroff(bool force)
    goto out;
    }

    - ret = call_usermodehelper_fns(argv[0], argv, envp, UMH_NO_WAIT,
    + ret = call_usermodehelper_fns(argv[0], argv, envp, UMH_NO_WAIT, 0, 0,
    NULL, argv_cleanup, NULL);
    out:
    if (likely(!ret))
    diff --git a/security/keys/request_key.c b/security/keys/request_key.c
    index 000e750..aa94dbb 100644
    --- a/security/keys/request_key.c
    +++ b/security/keys/request_key.c
    @@ -93,7 +93,7 @@ static void umh_keys_cleanup(struct subprocess_info *info)
    static int call_usermodehelper_keys(char *path, char **argv, char **envp,
    struct key *session_keyring, int wait)
    {
    - return call_usermodehelper_fns(path, argv, envp, wait,
    + return call_usermodehelper_fns(path, argv, envp, wait, 0, 0,
    umh_keys_init, umh_keys_cleanup,
    key_get(session_keyring));
    }
    --
    1.7.6.5



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