Re: [LTP] [PATCH v1] madvise11.c:Check loadable module before rmmod

[Wei Gao via ltp <ltp@lists.linux.it>]

On Fri, Mar 10, 2023 at 09:23:09PM -0500, Wei Gao via ltp wrote:
> On Fri, Mar 10, 2023 at 03:52:16PM +0100, Cyril Hrubis wrote:
> > Hi!
> > > +static int is_loadable_module(const char *modname)
> > > +{
> > > +	char command[MAX_BUF];
> > > +	char line[MAX_BUF];
> > > +	char *token;
> > > +
> > > +	sprintf(command, "lsmod | grep '^%s'", modname);
> > > +
> > > +	FILE *fp = popen(command, "r");
> > > +
> > > +	if (fp == NULL)
> > > +		tst_brk(TBROK, "Popen command %s failed", command);
> > > +
> > > +	if (fgets(line, MAX_BUF, fp) != NULL) {
> > > +		token = strtok(line, " \t\n");
> > > +		if (strcmp(token, modname) == 0) {
> > > +			pclose(fp);
> > > +			return 1;
> > > +		}
> > > +	}
> > > +
> > > +	pclose(fp);
> > > +	return 0;
> > > +}
> > 
> > The code already has if (!find_in_file("/proc/modules", HW_MODULE)), you
> > are reinventing the wheel.
> There is an issue happen during our test, the fail happen with following failed msg.
> rmmod: ERROR: Module hwpoison_inject is builtin.
> madvise11.c:356: TWARN: rmmod failed (1)
> 
> So i think before rmmod we should check this module can be rmmod or not.
> And every modules which can show in lsmod output, it means the module can be unload.
> I am not sure the output of /proc/modules contain ONLY loadable module, it maybe
> also can contain the buildin module so this function created.
> 
I have found modinfo is more stable way to check whether module is builtin or not.
I have update the patch to v3 now.
> > 
> > -- 
> > Cyril Hrubis
> > chrubis@suse.cz
> 
> -- 
> Mailing list info: https://lists.linux.it/listinfo/ltp

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