Re: [PATCH] staging: r8188eu: Use a Mutex instead of a binary Semaphore
From: Larry Finger
Date: Fri Oct 22 2021 - 13:52:39 EST
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@xxxxxxxxx>
Well done.
Acked-by: Larry Finger <Larry.Finger@xxxxxxxxxxxx>
---
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]);