Re: [PATCH 2/5] staging: wilc1000: fixes for undefined reference to `__this_module' error

[Ajay Singh <ajay.kathat@microchip.com>]

Hi Greg,

On Sun, 12 Aug 2018 13:35:55 +0200
Greg KH <gregkh@linuxfoundation.org> wrote:

> On Sun, Aug 12, 2018 at 10:17:42AM +0530, Ajay Singh wrote:
> > wilc_debug.o object file is included for both SDIO and SPI module.
> > When anyone(either SDIO or SPI) module is compiled as loaded module
> > and another as buildin module then below compilation error occurs.
> > 
> > "drivers/staging/wilc1000/wilc_debugfs.o:(.data+0x10): undefined
> > reference to `__this_module'"
> > 
> > Moved the declaration of file_operation variable in SDIO/SPI files
> > and pass this as parameter to wilc_debugfs_init(). Remove 'fops'
> > element from 'wilc_debugfs_info_t' struct, as its not required.
> > 
> > Fixes: 9abc44ba4e2f ("staging: wilc1000: fix TODO to compile spi
> > and sdio components in single module") Reported-by: kbuild test
> > robot <lkp@intel.com> Signed-off-by: Ajay Singh
> > <ajay.kathat@microchip.com> ---
> >  drivers/staging/wilc1000/linux_wlan.c   |  1 -
> >  drivers/staging/wilc1000/wilc_debugfs.c | 23
> > ++++++----------------- drivers/staging/wilc1000/wilc_sdio.c    |
> > 7 +++++++ drivers/staging/wilc1000/wilc_spi.c     |  7 +++++++
> >  drivers/staging/wilc1000/wilc_wlan_if.h |  7 ++++++-
> >  5 files changed, 26 insertions(+), 19 deletions(-)
> > 
> > diff --git a/drivers/staging/wilc1000/linux_wlan.c
> > b/drivers/staging/wilc1000/linux_wlan.c index 01cf4bd..37885ad
> > 100644 --- a/drivers/staging/wilc1000/linux_wlan.c
> > +++ b/drivers/staging/wilc1000/linux_wlan.c
> > @@ -1062,7 +1062,6 @@ int wilc_netdev_init(struct wilc **wilc,
> > struct device *dev, int io_type, if (!wl)
> >  		return -ENOMEM;
> >  
> > -	wilc_debugfs_init();
> >  	*wilc = wl;
> >  	wl->io_type = io_type;
> >  	wl->hif_func = ops;
> > diff --git a/drivers/staging/wilc1000/wilc_debugfs.c
> > b/drivers/staging/wilc1000/wilc_debugfs.c index c5f67c9..78c0831
> > 100644 --- a/drivers/staging/wilc1000/wilc_debugfs.c
> > +++ b/drivers/staging/wilc1000/wilc_debugfs.c
> > @@ -20,8 +20,8 @@ static struct dentry *wilc_dir;
> >  #define DBG_LEVEL_ALL	(DEBUG | INFO | WRN | ERR)
> >  static atomic_t WILC_DEBUG_LEVEL = ATOMIC_INIT(ERR);
> >  
> > -static ssize_t wilc_debug_level_read(struct file *file, char
> > __user *userbuf,
> > -				     size_t count, loff_t *ppos)
> > +ssize_t wilc_debug_level_read(struct file *file, char __user
> > *userbuf,
> > +			      size_t count, loff_t *ppos)
> >  {
> >  	char buf[128];
> >  	int res = 0;
> > @@ -36,9 +36,8 @@ static ssize_t wilc_debug_level_read(struct file
> > *file, char __user *userbuf, return
> > simple_read_from_buffer(userbuf, count, ppos, buf, res); }
> >  
> > -static ssize_t wilc_debug_level_write(struct file *filp,
> > -				      const char __user *buf,
> > size_t count,
> > -				      loff_t *ppos)
> > +ssize_t wilc_debug_level_write(struct file *filp, const char
> > __user *buf,
> > +			       size_t count, loff_t *ppos)
> >  {
> >  	int flag = 0;
> >  	int ret;
> > @@ -63,35 +62,25 @@ static ssize_t wilc_debug_level_write(struct
> > file *filp, return count;
> >  }
> >  
> > -#define FOPS(_open, _read, _write, _poll) { \
> > -		.owner	= THIS_MODULE, \
> > -		.open	= (_open), \
> > -		.read	= (_read), \
> > -		.write	= (_write), \
> > -		.poll		= (_poll), \
> > -}
> > -
> >  struct wilc_debugfs_info_t {
> >  	const char *name;
> >  	int perm;
> >  	unsigned int data;
> > -	const struct file_operations fops;
> >  };
> >  
> >  static struct wilc_debugfs_info_t debugfs_info = {
> >  	"wilc_debug_level",
> >  	0666,
> >  	(DEBUG | ERR),
> > -	FOPS(NULL, wilc_debug_level_read, wilc_debug_level_write,
> > NULL), };
> >  
> > -int wilc_debugfs_init(void)
> > +int wilc_debugfs_init(const struct file_operations *fops)
> >  {
> >  	struct wilc_debugfs_info_t *info = &debugfs_info;
> >  
> >  	wilc_dir = debugfs_create_dir("wilc_wifi", NULL);
> >  	debugfs_create_file(info->name, info->perm, wilc_dir,
> > &info->data,
> > -			    &info->fops);
> > +			    fops);
> >  
> >  	return 0;
> >  }
> > diff --git a/drivers/staging/wilc1000/wilc_sdio.c
> > b/drivers/staging/wilc1000/wilc_sdio.c index b2080d8..c1573f5 100644
> > --- a/drivers/staging/wilc1000/wilc_sdio.c
> > +++ b/drivers/staging/wilc1000/wilc_sdio.c
> > @@ -103,6 +103,12 @@ static int wilc_sdio_cmd53(struct wilc *wilc,
> > struct sdio_cmd53 *cmd) return ret;
> >  }
> >  
> > +static const struct file_operations sdio_debug_fops = {
> > +	.owner		= THIS_MODULE,
> > +	.read		= wilc_debug_level_read,
> > +	.write		= wilc_debug_level_write,
> > +};
> > +
> >  static int linux_sdio_probe(struct sdio_func *func,
> >  			    const struct sdio_device_id *id)
> >  {
> > @@ -126,6 +132,7 @@ static int linux_sdio_probe(struct sdio_func
> > *func, dev_err(&func->dev, "Couldn't initialize netdev\n");
> >  		return ret;
> >  	}
> > +	wilc_debugfs_init(&sdio_debug_fops);
> >  	sdio_set_drvdata(func, wilc);
> >  	wilc->dev = &func->dev;
> >  	wilc->gpio_irq = gpio;
> > diff --git a/drivers/staging/wilc1000/wilc_spi.c
> > b/drivers/staging/wilc1000/wilc_spi.c index 5517477..0376649 100644
> > --- a/drivers/staging/wilc1000/wilc_spi.c
> > +++ b/drivers/staging/wilc1000/wilc_spi.c
> > @@ -102,6 +102,12 @@ static u8 crc7(u8 crc, const u8 *buffer, u32
> > len) 
> >  #define USE_SPI_DMA				0
> >  
> > +static const struct file_operations spi_debug_fops = {
> > +	.owner		= THIS_MODULE,
> > +	.read		= wilc_debug_level_read,
> > +	.write		= wilc_debug_level_write,
> > +};
> 
> Wait, step back a second.  Why all of this work for a debugfs file
> that no one uses?  In wilc_debugfs.c there seems to only provide a
> single debugfs file to read and write a value that no one uses
> anywhere.
> 
> So why not a simple patch to just delete the wilc_debugfs.c file
> entirely?  Who even uses this debugfs file?  And if they do, what is
> it for?  What am I missing about how this is used?


Yes, currently only code to read and writing for "wilc_debug_level"
exists.

The main purpose for this file was to configure(enable/disable)
specific level debug logs to print.

Previously there were custom debug print API's like PRINT_K,
PRINT_INFO etc. Those portion of code is cleanup in previous patches
now only debugfs file is remaining. 

As of now this file is not used, but we had plans to use this
setting to enable/disable specific the debug prints. After completing
the cleanup activity for driver we had plans to take it up.


Regards,
Ajay