linux-kernel - Re: [PATCH 2/2] staging: lustre: obdclass: Add handling of error returned by lustre_cfg

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Message-Id: <FBDD8739-AC1E-461A-8449-28AC8534950F@intel.com>
Date:   Mon, 7 Nov 2016 17:46:00 -0500
From:   Oleg Drokin <oleg.drokin@...el.com>
To:     "Dilger, Andreas" <andreas.dilger@...el.com>
Cc:     Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        James Simmons <jsimmons@...radead.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Liu, Emoly" <emoly.liu@...el.com>,
        Lustre Development List <lustre-devel@...ts.lustre.org>,
        "devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>
Subject: Re: [PATCH 2/2] staging: lustre: obdclass: Add handling of error returned by lustre_cfg_new


On Nov 7, 2016, at 4:33 PM, Dilger, Andreas wrote:

> On Nov 6, 2016, at 10:26, Drokin, Oleg <oleg.drokin@...el.com> wrote:
>> 
>> Hello!
>> 
>> On Nov 6, 2016, at 12:11 PM, Christophe JAILLET wrote:
>> 
>>> 'lustre_cfg_new()' can return ERR_PTR(-ENOMEM).
>>> Handle these errors and propagate the error code to the callers.
>>> 
>>> Error handling has been rearranged in 'lustre_process_log()' with the
>>> addition of a label in order to free some resources.
>> 
>> I wonder if we should just make it return NULL on allocation failure,
>> and then at least the other error handling that is there (i.e. in your other patch)
>> would become correct.
>> This would make handling in mgc_apply_recover_logs incorrect, but it's already
>> geared towards this sort of handling anyway, as it discards the passed error
>> and sets ENOMEM unconditionally (just need to revert 3092c34a in a way).
> 
> I'd agree with Oleg that returning NULL is the preferable solution here. 
> 
> There are also callers of lustre_cfg_new() in class_config_llog_handler(),
> do_lcfg(), and lustre_end_log() that do not check error returns at all that
> should be fixed at the same time.

This patch was actually doing it.

> 
> Cheers, Andreas
> 
>>> 
>>> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
>>> ---
>>> drivers/staging/lustre/lustre/obdclass/obd_mount.c | 16 ++++++++++++++--
>>> 1 file changed, 14 insertions(+), 2 deletions(-)
>>> 
>>> diff --git a/drivers/staging/lustre/lustre/obdclass/obd_mount.c b/drivers/staging/lustre/lustre/obdclass/obd_mount.c
>>> index 59fbc29aae94..5473615cd338 100644
>>> --- a/drivers/staging/lustre/lustre/obdclass/obd_mount.c
>>> +++ b/drivers/staging/lustre/lustre/obdclass/obd_mount.c
>>> @@ -89,11 +89,14 @@ int lustre_process_log(struct super_block *sb, char *logname,
>>> 	lustre_cfg_bufs_set(bufs, 2, cfg, sizeof(*cfg));
>>> 	lustre_cfg_bufs_set(bufs, 3, &sb, sizeof(sb));
>>> 	lcfg = lustre_cfg_new(LCFG_LOG_START, bufs);
>>> +	if (IS_ERR(lcfg)) {
>>> +		rc = PTR_ERR(lcfg);
>>> +		goto out_free;
>>> +	}
>>> +
>>> 	rc = obd_process_config(mgc, sizeof(*lcfg), lcfg);
>>> 	lustre_cfg_free(lcfg);
>>> 
>>> -	kfree(bufs);
>>> -
>>> 	if (rc == -EINVAL)
>>> 		LCONSOLE_ERROR_MSG(0x15b, "%s: The configuration from log '%s' failed from the MGS (%d).  Make sure this client and the MGS are running compatible versions of Lustre.\n",
>>> 				   mgc->obd_name, logname, rc);
>>> @@ -104,6 +107,9 @@ int lustre_process_log(struct super_block *sb, char *logname,
>>> 				   rc);
>>> 
>>> 	/* class_obd_list(); */
>>> +
>>> +out_free:
>>> +	kfree(bufs);
>>> 	return rc;
>>> }
>>> EXPORT_SYMBOL(lustre_process_log);
>>> @@ -127,6 +133,9 @@ int lustre_end_log(struct super_block *sb, char *logname,
>>> 	if (cfg)
>>> 		lustre_cfg_bufs_set(&bufs, 2, cfg, sizeof(*cfg));
>>> 	lcfg = lustre_cfg_new(LCFG_LOG_END, &bufs);
>>> +	if (IS_ERR(lcfg))
>>> +		return PTR_ERR(lcfg);
>>> +
>>> 	rc = obd_process_config(mgc, sizeof(*lcfg), lcfg);
>>> 	lustre_cfg_free(lcfg);
>>> 	return rc;
>>> @@ -159,6 +168,9 @@ static int do_lcfg(char *cfgname, lnet_nid_t nid, int cmd,
>>> 		lustre_cfg_bufs_set_string(&bufs, 4, s4);
>>> 
>>> 	lcfg = lustre_cfg_new(cmd, &bufs);
>>> +	if (IS_ERR(lcfg))
>>> +		return PTR_ERR(lcfg);
>>> +
>>> 	lcfg->lcfg_nid = nid;
>>> 	rc = class_process_config(lcfg);
>>> 	lustre_cfg_free(lcfg);
>>> -- 
>>> 2.9.3
>>