[lustre-devel] [PATCH] staging: lustre: grab the cld->cld_lock mutex unconditionally

[Cihangir Akturk]

On Thu, Aug 03, 2017 at 08:31:15PM +0300, Cihangir Akturk wrote:
> On Thu, Aug 03, 2017 at 05:52:44PM +0100, James Simmons wrote:
> > 
> > > Instead of using the locked variable as a helper to determine the state
> > > of the mutex cld->cld_lock, expand the scope of the recover_cld variable
> > > and assign to the cld->cld_recover variable depending on whether the
> > > value of the recover_cld variable is valid or not.
> > > 
> > > As a bonus, code size is slightly reduced.
> > > 
> > > before:
> > > text    data     bss     dec     hex filename
> > > 26188    2256    4208   32652    7f8c drivers/staging/lustre/lustre/mgc/mgc_request.o
> > > 
> > > after:
> > > text    data     bss     dec     hex filename
> > > 26140    2256    4208   32604    7f5c drivers/staging/lustre/lustre/mgc/mgc_request.o
> > > 
> > > Additionally silences the following warning reported by coccinelle:
> > > 
> > > drivers/staging/lustre/lustre/mgc/mgc_request.c:359:2-12: second lock on
> > > line 365
> > > 
> > > Signed-off-by: Cihangir Akturk <cakturk at gmail.com>
> > > ---
> > >  drivers/staging/lustre/lustre/mgc/mgc_request.c | 13 ++++---------
> > >  1 file changed, 4 insertions(+), 9 deletions(-)
> > > 
> > > diff --git a/drivers/staging/lustre/lustre/mgc/mgc_request.c b/drivers/staging/lustre/lustre/mgc/mgc_request.c
> > > index eee0b66..6718474 100644
> > > --- a/drivers/staging/lustre/lustre/mgc/mgc_request.c
> > > +++ b/drivers/staging/lustre/lustre/mgc/mgc_request.c
> > > @@ -288,7 +288,7 @@ config_log_add(struct obd_device *obd, char *logname,
> > >  	struct config_llog_data *cld;
> > >  	struct config_llog_data *sptlrpc_cld;
> > >  	struct config_llog_data *params_cld;
> > > -	bool locked = false;
> > > +	struct config_llog_data *recover_cld = ERR_PTR(-EINVAL);
> > >  	char			seclogname[32];
> > >  	char			*ptr;
> > >  	int			rc;
> > 
> > Why not just set it to NULL? 
> 
> Hi,
> 
> Because config_recover_log_add() function does not return NULL on
> error. And I don't think IS_ERR on NULL pointer returns true.

Sorry, I've just realized I was wrong. Setting it to null makes
perfect sense.

Thanks.

> 
> Thanks.
> 
> > > @@ -338,8 +338,6 @@ config_log_add(struct obd_device *obd, char *logname,
> > >  
> > >  	LASSERT(lsi->lsi_lmd);
> > >  	if (!(lsi->lsi_lmd->lmd_flags & LMD_FLG_NOIR)) {
> > > -		struct config_llog_data *recover_cld;
> > > -
> > >  		ptr = strrchr(seclogname, '-');
> > >  		if (ptr) {
> > >  			*ptr = 0;
> > > @@ -355,14 +353,11 @@ config_log_add(struct obd_device *obd, char *logname,
> > >  			rc = PTR_ERR(recover_cld);
> > >  			goto out_cld;
> > >  		}
> > > -
> > > -		mutex_lock(&cld->cld_lock);
> > > -		locked = true;
> > > -		cld->cld_recover = recover_cld;
> > >  	}
> > >  
> > > -	if (!locked)
> > > -		mutex_lock(&cld->cld_lock);
> > > +	mutex_lock(&cld->cld_lock);
> > > +	if (!IS_ERR(recover_cld))
> > 
> > Don't need this test if by default recover_cld = NULL.
> > 
> > > +		cld->cld_recover = recover_cld;
> > >  	cld->cld_params = params_cld;
> > >  	cld->cld_sptlrpc = sptlrpc_cld;
> > >  	mutex_unlock(&cld->cld_lock);
> > > -- 
> > > 2.7.4
> > > 
> > > _______________________________________________
> > > devel mailing list
> > > devel at linuxdriverproject.org
> > > http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
> > >