[PATCH v3 0/3] staging: r8188eu: use completions and clean rtw_cmd_thread()

[PATCH v3 0/3] staging: r8188eu: use completions and clean rtw_cmd_thread()

[Fabio M. De Francesco]

This series replaces two semaphores with three completion variables
in rtw_cmd_thread(). Completions variables are better suited for the
purposes that are explained in detail in the commit messages of patches
1/3 and 2/3. Furthermore, patch 3/3 removes a redundant 'if' statement
from that same rtw_cmd_thread().

Tested with ASUSTek Computer, Inc. Realtek 8188EUS [USB-N10 Nano]

Many thanks to Dan Carpenter <dan.carpenter@oracle.com> who helped with
his review of the RFC Patch.

v2 => v3:
	Patch 1/3:
		No changes;
	Patch 2/3:
		No changes;
	Patch 3/3:
		Furher process the commit message according to a review
		by Greg Kroah-Hartman <gregkh@linuxfoundation.org>>.

v1 => v2:
        Patch 1/3: 
		No changes;
        Patch 2/3: 
		Replace wait_for_completion_killable() with
		wait_for_completion() because killing the kthread is
                not allowed and so there is no need for killable
                wait;
        Patch 3/3: 
		No changes.

Fabio M. De Francesco (3):
  staging: r8188eu: Use completions for signaling start / end kthread
  staging: r8188eu: Use completions for signaling enqueueing
  staging: r8188eu: Remove redundant 'if' statement

 drivers/staging/r8188eu/core/rtw_cmd.c    | 20 +++++++-------------
 drivers/staging/r8188eu/include/rtw_cmd.h |  5 +++--
 drivers/staging/r8188eu/os_dep/os_intfs.c |  8 +++++---
 3 files changed, 15 insertions(+), 18 deletions(-)

-- 
2.33.0

[PATCH v3 1/3] staging: r8188eu: Use completions for signaling start / end kthread

[Fabio M. De Francesco]

rtw_cmd_thread() "up(s)" a semaphore twice, first to notify callers when
its execution is started and then to notify when it is about to end.

It makes the same semaphore go "up" twice in the same thread. This
construct makes Smatch to warn of duplicate "up(s)".

This thread uses interruptible semaphores where instead completions are
more suitable. For this purpose it calls an helper (_rtw_down_sema())
that returns values that are never checked. It may lead to bugs.

To address the above-mentioned issues, use two completions variables
instead of semaphores. Use the uninterruptible versions of
wake_for_completion*() because the interruptible / killable versions are
not necessary.

Tested with "ASUSTek Computer, Inc. Realtek 8188EUS [USB-N10 Nano]".

Acked-by: Phillip Potter <phil@philpotter.co.uk>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
---
 drivers/staging/r8188eu/core/rtw_cmd.c    | 7 ++++---
 drivers/staging/r8188eu/include/rtw_cmd.h | 3 ++-
 drivers/staging/r8188eu/os_dep/os_intfs.c | 6 ++++--
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/staging/r8188eu/core/rtw_cmd.c b/drivers/staging/r8188eu/core/rtw_cmd.c
index b834fac41627..bdf0d0160070 100644
--- a/drivers/staging/r8188eu/core/rtw_cmd.c
+++ b/drivers/staging/r8188eu/core/rtw_cmd.c
@@ -23,7 +23,8 @@ static int _rtw_init_cmd_priv(struct cmd_priv *pcmdpriv)
 
 	sema_init(&pcmdpriv->cmd_queue_sema, 0);
 	/* sema_init(&(pcmdpriv->cmd_done_sema), 0); */
-	sema_init(&pcmdpriv->terminate_cmdthread_sema, 0);
+	init_completion(&pcmdpriv->start_cmd_thread);
+	init_completion(&pcmdpriv->stop_cmd_thread);
 
 	rtw_init_queue(&pcmdpriv->cmd_queue);
 
@@ -246,7 +247,7 @@ int rtw_cmd_thread(void *context)
 	pcmdbuf = pcmdpriv->cmd_buf;
 
 	pcmdpriv->cmdthd_running = true;
-	up(&pcmdpriv->terminate_cmdthread_sema);
+	complete(&pcmdpriv->start_cmd_thread);
 
 	while (1) {
 		if (_rtw_down_sema(&pcmdpriv->cmd_queue_sema) == _FAIL)
@@ -327,7 +328,7 @@ int rtw_cmd_thread(void *context)
 		rtw_free_cmd_obj(pcmd);
 	} while (1);
 
-	up(&pcmdpriv->terminate_cmdthread_sema);
+	complete(&pcmdpriv->stop_cmd_thread);
 
 	thread_exit();
 }
diff --git a/drivers/staging/r8188eu/include/rtw_cmd.h b/drivers/staging/r8188eu/include/rtw_cmd.h
index 83fbb922db2c..b6266e3e2c40 100644
--- a/drivers/staging/r8188eu/include/rtw_cmd.h
+++ b/drivers/staging/r8188eu/include/rtw_cmd.h
@@ -34,7 +34,8 @@ struct cmd_obj {
 
 struct cmd_priv {
 	struct semaphore cmd_queue_sema;
-	struct semaphore terminate_cmdthread_sema;
+	struct completion start_cmd_thread;
+	struct completion stop_cmd_thread;
 	struct __queue cmd_queue;
 	u8	cmd_seq;
 	u8	*cmd_buf;	/* shall be non-paged, and 4 bytes aligned */
diff --git a/drivers/staging/r8188eu/os_dep/os_intfs.c b/drivers/staging/r8188eu/os_dep/os_intfs.c
index e7964a048c99..0bcea66f550b 100644
--- a/drivers/staging/r8188eu/os_dep/os_intfs.c
+++ b/drivers/staging/r8188eu/os_dep/os_intfs.c
@@ -385,7 +385,8 @@ u32 rtw_start_drv_threads(struct adapter *padapter)
 	if (IS_ERR(padapter->cmdThread))
 		_status = _FAIL;
 	else
-		_rtw_down_sema(&padapter->cmdpriv.terminate_cmdthread_sema); /* wait for cmd_thread to run */
+		/* wait for rtw_cmd_thread() to start running */
+		wait_for_completion(&padapter->cmdpriv.start_cmd_thread);
 
 	return _status;
 }
@@ -395,7 +396,8 @@ void rtw_stop_drv_threads(struct adapter *padapter)
 	/* Below is to termindate rtw_cmd_thread & event_thread... */
 	up(&padapter->cmdpriv.cmd_queue_sema);
 	if (padapter->cmdThread)
-		_rtw_down_sema(&padapter->cmdpriv.terminate_cmdthread_sema);
+		/* wait for rtw_cmd_thread() to stop running */
+		wait_for_completion(&padapter->cmdpriv.stop_cmd_thread);
 }
 
 static u8 rtw_init_default_value(struct adapter *padapter)
-- 
2.33.0

[PATCH v3 2/3] staging: r8188eu: Use completions for signaling enqueueing

[Fabio M. De Francesco]

rtw_enqueue_cmd() uses a semaphore to notify rtw_cmd_thread() that it
has enqueued commands. rtw_cmd_thread() "down(s)" in interruptible mode
to wait to be notified.

Use completion variables because they are better suited for the purpose.

In rtw_cmd_thread(), wait in uninterruptible mode, even if the original
code uses down_interruptible(), because the interruption of
rtw_cmd_thread() is not allowed and unwanted.

Tested with "ASUSTek Computer, Inc. Realtek 8188EUS [USB-N10 Nano]".

Acked-by: Phillip Potter <phil@philpotter.co.uk>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
---
 drivers/staging/r8188eu/core/rtw_cmd.c    | 7 +++----
 drivers/staging/r8188eu/include/rtw_cmd.h | 2 +-
 drivers/staging/r8188eu/os_dep/os_intfs.c | 2 +-
 3 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/staging/r8188eu/core/rtw_cmd.c b/drivers/staging/r8188eu/core/rtw_cmd.c
index bdf0d0160070..3b07328704bb 100644
--- a/drivers/staging/r8188eu/core/rtw_cmd.c
+++ b/drivers/staging/r8188eu/core/rtw_cmd.c
@@ -21,7 +21,7 @@ static int _rtw_init_cmd_priv(struct cmd_priv *pcmdpriv)
 {
 	int res = _SUCCESS;
 
-	sema_init(&pcmdpriv->cmd_queue_sema, 0);
+	init_completion(&pcmdpriv->enqueue_cmd);
 	/* sema_init(&(pcmdpriv->cmd_done_sema), 0); */
 	init_completion(&pcmdpriv->start_cmd_thread);
 	init_completion(&pcmdpriv->stop_cmd_thread);
@@ -198,7 +198,7 @@ u32 rtw_enqueue_cmd(struct cmd_priv *pcmdpriv, struct cmd_obj *cmd_obj)
 	res = _rtw_enqueue_cmd(&pcmdpriv->cmd_queue, cmd_obj);
 
 	if (res == _SUCCESS)
-		up(&pcmdpriv->cmd_queue_sema);
+		complete(&pcmdpriv->enqueue_cmd);
 
 exit:
 
@@ -250,8 +250,7 @@ int rtw_cmd_thread(void *context)
 	complete(&pcmdpriv->start_cmd_thread);
 
 	while (1) {
-		if (_rtw_down_sema(&pcmdpriv->cmd_queue_sema) == _FAIL)
-			break;
+		wait_for_completion(&pcmdpriv->enqueue_cmd);
 
 		if (padapter->bDriverStopped ||
 		    padapter->bSurpriseRemoved) {
diff --git a/drivers/staging/r8188eu/include/rtw_cmd.h b/drivers/staging/r8188eu/include/rtw_cmd.h
index b6266e3e2c40..47c3c80cc24a 100644
--- a/drivers/staging/r8188eu/include/rtw_cmd.h
+++ b/drivers/staging/r8188eu/include/rtw_cmd.h
@@ -33,7 +33,7 @@ struct cmd_obj {
 };
 
 struct cmd_priv {
-	struct semaphore cmd_queue_sema;
+	struct completion enqueue_cmd;
 	struct completion start_cmd_thread;
 	struct completion stop_cmd_thread;
 	struct __queue cmd_queue;
diff --git a/drivers/staging/r8188eu/os_dep/os_intfs.c b/drivers/staging/r8188eu/os_dep/os_intfs.c
index 0bcea66f550b..96e9897085fe 100644
--- a/drivers/staging/r8188eu/os_dep/os_intfs.c
+++ b/drivers/staging/r8188eu/os_dep/os_intfs.c
@@ -394,7 +394,7 @@ u32 rtw_start_drv_threads(struct adapter *padapter)
 void rtw_stop_drv_threads(struct adapter *padapter)
 {
 	/* Below is to termindate rtw_cmd_thread & event_thread... */
-	up(&padapter->cmdpriv.cmd_queue_sema);
+	complete(&padapter->cmdpriv.enqueue_cmd);
 	if (padapter->cmdThread)
 		/* wait for rtw_cmd_thread() to stop running */
 		wait_for_completion(&padapter->cmdpriv.stop_cmd_thread);
-- 
2.33.0

[PATCH v3 3/3] staging: r8188eu: Remove redundant 'if' statement

[Fabio M. De Francesco]

Remove the redundant first 'if' statement of two identical ones.

In rtw_cmd_thread() there are two identical 'if' statement, one
immediately after the other. They check whether or not the device is
removed or the driver is stopped and, if true, they break a 'while'
loop.

The only noteworthy context difference is that the second statement is
within a block labelled "_next". The code has a 'goto' to the "_next"
label so that the checking is performed each time the above directive
is encountered. Instead, the first 'if' is before the "_next" label.

One of the two must be removed and that it must be the one before the
label because "bSurpriseRemoved" as well as "bDriverStopped" may be
changed asynchronously by other code of the driver and so they should be
checked at each jump to "_next".

Tested with "ASUSTek Computer, Inc. Realtek 8188EUS [USB-N10 Nano]".

Acked-by: Martin Kaiser <martin@kaiser.cx>
Acked-by: Phillip Potter <phil@philpotter.co.uk>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
---
 drivers/staging/r8188eu/core/rtw_cmd.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/drivers/staging/r8188eu/core/rtw_cmd.c b/drivers/staging/r8188eu/core/rtw_cmd.c
index 3b07328704bb..5d5f25364b2f 100644
--- a/drivers/staging/r8188eu/core/rtw_cmd.c
+++ b/drivers/staging/r8188eu/core/rtw_cmd.c
@@ -252,12 +252,6 @@ int rtw_cmd_thread(void *context)
 	while (1) {
 		wait_for_completion(&pcmdpriv->enqueue_cmd);
 
-		if (padapter->bDriverStopped ||
-		    padapter->bSurpriseRemoved) {
-			DBG_88E("%s: DriverStopped(%d) SurpriseRemoved(%d) break at line %d\n",
-				__func__, padapter->bDriverStopped, padapter->bSurpriseRemoved, __LINE__);
-			break;
-		}
 _next:
 		if (padapter->bDriverStopped ||
 		    padapter->bSurpriseRemoved) {
-- 
2.33.0