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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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