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    Subject[PATCH] firmware_class: Move request_firmware_nowait() to workqueues
    Date
    Oddly enough a work_struct was already part of the firmware_work
    structure but nobody was using it. Instead of creating a new
    kthread for each request_firmware_nowait() just schedule the work
    on the system workqueue. This should avoid some overhead in
    forking new threads when they're not strictly necessary if
    workqueues are available.

    Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
    Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Cc: Kay Sievers <kay.sievers@vrfy.org>
    Cc: Rafael J. Wysocki <rjw@sisk.pl>
    ---

    I saw this while looking at this problem we're having.

    drivers/base/firmware_class.c | 29 +++++++----------------------
    1 file changed, 7 insertions(+), 22 deletions(-)

    diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
    index 6c9387d..1010c06 100644
    --- a/drivers/base/firmware_class.c
    +++ b/drivers/base/firmware_class.c
    @@ -16,7 +16,7 @@
    #include <linux/interrupt.h>
    #include <linux/bitops.h>
    #include <linux/mutex.h>
    -#include <linux/kthread.h>
    +#include <linux/workqueue.h>
    #include <linux/highmem.h>
    #include <linux/firmware.h>
    #include <linux/slab.h>
    @@ -629,25 +629,18 @@ struct firmware_work {
    bool uevent;
    };

    -static int request_firmware_work_func(void *arg)
    +static void request_firmware_work_func(struct work_struct *work)
    {
    - struct firmware_work *fw_work = arg;
    + struct firmware_work *fw_work;
    const struct firmware *fw;
    - int ret;
    -
    - if (!arg) {
    - WARN_ON(1);
    - return 0;
    - }
    + fw_work = container_of(work, struct firmware_work, work);

    - ret = _request_firmware(&fw, fw_work->name, fw_work->device,
    + _request_firmware(&fw, fw_work->name, fw_work->device,
    fw_work->uevent, true);
    fw_work->cont(fw, fw_work->context);

    module_put(fw_work->module);
    kfree(fw_work);
    -
    - return ret;
    }

    /**
    @@ -673,7 +666,6 @@ request_firmware_nowait(
    const char *name, struct device *device, gfp_t gfp, void *context,
    void (*cont)(const struct firmware *fw, void *context))
    {
    - struct task_struct *task;
    struct firmware_work *fw_work;

    fw_work = kzalloc(sizeof (struct firmware_work), gfp);
    @@ -692,15 +684,8 @@ request_firmware_nowait(
    return -EFAULT;
    }

    - task = kthread_run(request_firmware_work_func, fw_work,
    - "firmware/%s", name);
    - if (IS_ERR(task)) {
    - fw_work->cont(NULL, fw_work->context);
    - module_put(fw_work->module);
    - kfree(fw_work);
    - return PTR_ERR(task);
    - }
    -
    + INIT_WORK(&fw_work->work, request_firmware_work_func);
    + schedule_work(&fw_work->work);
    return 0;
    }

    --
    Sent by an employee of the Qualcomm Innovation Center, Inc.
    The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.


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