linux-kernel - [PATCH v4 0/3] *** staging: wilc1000: Replace semaphores ***

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Message-Id: <1466660512-14935-1-git-send-email-binoy.jayan@linaro.org>
Date:	Thu, 23 Jun 2016 11:11:49 +0530
From:	Binoy Jayan <binoy.jayan@...aro.org>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	Johnny Kim <johnny.kim@...el.com>,
	Austin Shin <austin.shin@...el.com>,
	Chris Park <chris.park@...el.com>,
	Tony Cho <tony.cho@...el.com>, Glen Lee <glen.lee@...el.com>,
	Leo Kim <leo.kim@...el.com>, Arnd Bergmann <arnd@...db.de>,
	linux-wireless@...r.kernel.org, devel@...verdev.osuosl.org,
	linux-kernel@...r.kernel.org, Binoy Jayan <binoy.jayan@...aro.org>
Subject: [PATCH v4 0/3] *** staging: wilc1000: Replace semaphores ***

Hi,

Thank you Arnd for patiently reviewing this patch series multiple times and
apologies to everyone for spamming you inboxes with a patch (v3) that does
not even build. It was due to an uncommited change in my git repo before
generating the patch. It is corrected in v4.

This patchset [v4] is part of the second patch series for 'wilc1000'.
The original patch series consisted 7 patches of which only the first 5
are good. The patch 6 and 7 are being worked on in this series
in a different way.

This patch series removes the semaphore 'sem' in 'wilc1000' and also
restructures the implementation of kthread / message_queue logic with
a create_singlethread_workqueue() / queue_work() setup.

These are part of a bigger effort to eliminate all semaphores
from the linux kernel.

They build correctly (individually and as a whole).

NB: The changes are untested

Discussion carried forward from previous patchset [v2]

Rework on the review comments by Arnd w.r.t. v1

struct message_queue can be removed since
 - after the workqueue conversion, mq->sem is no longer needed
 - recv_count is not needed, it just counts the number of entries in the list
 - struct wilc' pointer can be retrieved from the host_if_msg, (vif->wilc)
 - the message list is not needed because we always look only at the
   first entry, except in wilc_mq_destroy(), but it would be better
   to just call destroy_workqueue(), which also drains the remaining work.
 - the exiting flag is also handled by destroy_workqueue()   
 - with everything else gone, the spinlock is also not needed any more.

Do 'kfree' only at the end of 'host_if_work' 

wilc_initialized is always '1' so the conditional 'wilc_mq_send'
in 'hostIFthread' can be removed.

A connect command (HOST_IF_MSG_CONNECT) does not complete while scan is ongoing. 
So, the special handling of this command needs to be preserved.

Use create_singlethread_workqueue() instead of alloc_workqueue(), so that
we stay closer to the current behavior by having the thread run only
on one CPU at a time and not having a 'dedicated' thread for each.

Split the patch to seperate interface changes to 'wilc_mq_send'
    No easy way found to split the patch to change the interface
    'wilc_mq_send' and to 'wilc_enqueue_cmd' as the parameters 
    'mq' 'send_buf' and 'send_buf_size' itself are part of the message
    queue implementation.

New changes in v3

Rework on the review comments by Arnd w.r.t. v2
 - Remove forward declaration for wilc_enqueue_cmd
 - Change the interface 'wilc_mq_send' in a different patch
 - Avoid change in indentation in host_if_work and move it to
   a different patch

Cannot remove forward declaration of local function 'host_if_work'
   since there is a mutual dependency.

New changes in v4

Remove unused identifier 'hif_msg_q' which causes the build error.

	Binoy

Binoy Jayan (3):
  staging: wilc1000: message_queue: Move code to host interface
  staging: wilc1000: Replace kthread with workqueue for host interface
  staging: wilc1000: Change interface wilc_mq_send to wilc_enqueue_cmd

 drivers/staging/wilc1000/Makefile         |   1 -
 drivers/staging/wilc1000/TODO             |   5 +
 drivers/staging/wilc1000/host_interface.c | 396 +++++++++++++++---------------
 drivers/staging/wilc1000/wilc_msgqueue.c  | 144 -----------
 drivers/staging/wilc1000/wilc_msgqueue.h  |  28 ---
 5 files changed, 204 insertions(+), 370 deletions(-)
 delete mode 100644 drivers/staging/wilc1000/wilc_msgqueue.c
 delete mode 100644 drivers/staging/wilc1000/wilc_msgqueue.h

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