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Date: Fri, 22 Oct 2021 12:52:33 -0500
From: Larry Finger <Larry.Finger@...inger.net>
To: "Fabio M. De Francesco" <fmdefrancesco@...il.com>,
Phillip Potter <phil@...lpotter.co.uk>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: r8188eu: Use a Mutex instead of a binary
Semaphore
On 10/22/21 12:19, Fabio M. De Francesco wrote:
> Use a Mutex instead of a binary Semaphore for the purpose of enforcing
> mutual exclusive access to the "pwrctrl_priv" structure.
>
> Mutexes are sleeping locks similar to Semaphores with a 'count' of one
> (like binary Semaphores), however they have a simpler interface, more
> efficient performance, and additional constraints.
>
> There is no change in the logic of the new code; however it is more
> simple because it gets rid of four unnecessary wrappers:
> _init_pwrlock(), _enter_pwrlock(),_exit_pwrlock(), _rtw_down_sema().
>
> Actually, there is a change in the state in which the code waits for
> acquiring locks, because it makes it in an uninterruptible state
> (instead the old code used down_interruptibe()). Interruptible
> waits are neither required nor wanted in this driver.
>
> Tested with ASUSTek Computer, Inc. Realtek 8188EUS [USB-N10 Nano].
>
> Signed-off-by: Fabio M. De Francesco <fmdefrancesco@...il.com>
Well done.
Acked-by: Larry Finger <Larry.Finger@...inger.net>
> ---
> drivers/staging/r8188eu/core/rtw_pwrctrl.c | 10 +++++-----
> drivers/staging/r8188eu/include/osdep_service.h | 2 --
> drivers/staging/r8188eu/include/rtw_pwrctrl.h | 17 +----------------
> drivers/staging/r8188eu/os_dep/osdep_service.c | 8 --------
> drivers/staging/r8188eu/os_dep/usb_intf.c | 8 ++++----
> 5 files changed, 10 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/staging/r8188eu/core/rtw_pwrctrl.c b/drivers/staging/r8188eu/core/rtw_pwrctrl.c
> index 19cac5814ea4..5d595cf2a47e 100644
> --- a/drivers/staging/r8188eu/core/rtw_pwrctrl.c
> +++ b/drivers/staging/r8188eu/core/rtw_pwrctrl.c
> @@ -21,7 +21,7 @@ void ips_enter(struct adapter *padapter)
> return;
> }
>
> - _enter_pwrlock(&pwrpriv->lock);
> + mutex_lock(&pwrpriv->lock);
>
> pwrpriv->bips_processing = true;
>
> @@ -42,7 +42,7 @@ void ips_enter(struct adapter *padapter)
> }
> pwrpriv->bips_processing = false;
>
> - _exit_pwrlock(&pwrpriv->lock);
> + mutex_unlock(&pwrpriv->lock);
> }
>
> int ips_leave(struct adapter *padapter)
> @@ -53,7 +53,7 @@ int ips_leave(struct adapter *padapter)
> int result = _SUCCESS;
> int keyid;
>
> - _enter_pwrlock(&pwrpriv->lock);
> + mutex_lock(&pwrpriv->lock);
>
> if ((pwrpriv->rf_pwrstate == rf_off) && (!pwrpriv->bips_processing)) {
> pwrpriv->bips_processing = true;
> @@ -87,7 +87,7 @@ int ips_leave(struct adapter *padapter)
> pwrpriv->bpower_saving = false;
> }
>
> - _exit_pwrlock(&pwrpriv->lock);
> + mutex_unlock(&pwrpriv->lock);
>
> return result;
> }
> @@ -337,7 +337,7 @@ void rtw_init_pwrctrl_priv(struct adapter *padapter)
> {
> struct pwrctrl_priv *pwrctrlpriv = &padapter->pwrctrlpriv;
>
> - _init_pwrlock(&pwrctrlpriv->lock);
> + mutex_init(&pwrctrlpriv->lock);
> pwrctrlpriv->rf_pwrstate = rf_on;
> pwrctrlpriv->ips_enter_cnts = 0;
> pwrctrlpriv->ips_leave_cnts = 0;
> diff --git a/drivers/staging/r8188eu/include/osdep_service.h b/drivers/staging/r8188eu/include/osdep_service.h
> index 886a1b6f30b4..efab3a97eb46 100644
> --- a/drivers/staging/r8188eu/include/osdep_service.h
> +++ b/drivers/staging/r8188eu/include/osdep_service.h
> @@ -141,8 +141,6 @@ extern unsigned char RSN_TKIP_CIPHER[4];
>
> void *rtw_malloc2d(int h, int w, int size);
>
> -u32 _rtw_down_sema(struct semaphore *sema);
> -
> #define rtw_init_queue(q) \
> do { \
> INIT_LIST_HEAD(&((q)->queue)); \
> diff --git a/drivers/staging/r8188eu/include/rtw_pwrctrl.h b/drivers/staging/r8188eu/include/rtw_pwrctrl.h
> index 04236e42fbf9..b19ef796ab54 100644
> --- a/drivers/staging/r8188eu/include/rtw_pwrctrl.h
> +++ b/drivers/staging/r8188eu/include/rtw_pwrctrl.h
> @@ -27,21 +27,6 @@ enum power_mgnt {
> PS_MODE_NUM
> };
>
> -static inline void _init_pwrlock(struct semaphore *plock)
> -{
> - sema_init(plock, 1);
> -}
> -
> -static inline void _enter_pwrlock(struct semaphore *plock)
> -{
> - _rtw_down_sema(plock);
> -}
> -
> -static inline void _exit_pwrlock(struct semaphore *plock)
> -{
> - up(plock);
> -}
> -
> #define LPS_DELAY_TIME 1*HZ /* 1 sec */
>
> /* RF state. */
> @@ -60,7 +45,7 @@ enum { /* for ips_mode */
> };
>
> struct pwrctrl_priv {
> - struct semaphore lock;
> + struct mutex lock; /* Mutex used to protect struct pwrctrl_priv */
>
> u8 pwr_mode;
> u8 smart_ps;
> diff --git a/drivers/staging/r8188eu/os_dep/osdep_service.c b/drivers/staging/r8188eu/os_dep/osdep_service.c
> index 6bee194fc35d..59bdd0abea7e 100644
> --- a/drivers/staging/r8188eu/os_dep/osdep_service.c
> +++ b/drivers/staging/r8188eu/os_dep/osdep_service.c
> @@ -42,14 +42,6 @@ Otherwise, there will be racing condition.
> Caller must check if the list is empty before calling rtw_list_delete
> */
>
> -u32 _rtw_down_sema(struct semaphore *sema)
> -{
> - if (down_interruptible(sema))
> - return _FAIL;
> - else
> - return _SUCCESS;
> -}
> -
> inline u32 rtw_systime_to_ms(u32 systime)
> {
> return systime * 1000 / HZ;
> diff --git a/drivers/staging/r8188eu/os_dep/usb_intf.c b/drivers/staging/r8188eu/os_dep/usb_intf.c
> index 7ed9f5f54472..fc74c93272a8 100644
> --- a/drivers/staging/r8188eu/os_dep/usb_intf.c
> +++ b/drivers/staging/r8188eu/os_dep/usb_intf.c
> @@ -233,7 +233,7 @@ static int rtw_suspend(struct usb_interface *pusb_intf, pm_message_t message)
> rtw_cancel_all_timer(padapter);
> LeaveAllPowerSaveMode(padapter);
>
> - _enter_pwrlock(&pwrpriv->lock);
> + mutex_lock(&pwrpriv->lock);
> /* s1. */
> if (pnetdev) {
> netif_carrier_off(pnetdev);
> @@ -262,7 +262,7 @@ static int rtw_suspend(struct usb_interface *pusb_intf, pm_message_t message)
> rtw_free_network_queue(padapter, true);
>
> rtw_dev_unload(padapter);
> - _exit_pwrlock(&pwrpriv->lock);
> + mutex_unlock(&pwrpriv->lock);
>
> if (check_fwstate(pmlmepriv, _FW_UNDER_SURVEY))
> rtw_indicate_scan_done(padapter, 1);
> @@ -291,7 +291,7 @@ static int rtw_resume(struct usb_interface *pusb_intf)
> pnetdev = padapter->pnetdev;
> pwrpriv = &padapter->pwrctrlpriv;
>
> - _enter_pwrlock(&pwrpriv->lock);
> + mutex_lock(&pwrpriv->lock);
> rtw_reset_drv_sw(padapter);
> if (pwrpriv)
> pwrpriv->bkeepfwalive = false;
> @@ -303,7 +303,7 @@ static int rtw_resume(struct usb_interface *pusb_intf)
> netif_device_attach(pnetdev);
> netif_carrier_on(pnetdev);
>
> - _exit_pwrlock(&pwrpriv->lock);
> + mutex_unlock(&pwrpriv->lock);
>
> if (padapter->pid[1] != 0) {
> DBG_88E("pid[1]:%d\n", padapter->pid[1]);
>
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