From: Cyril Hrubis <chrubis@suse.cz>
To: Filippo Storniolo <fstornio@redhat.com>
Cc: ltp@lists.linux.it
Subject: Re: [LTP] [PATCH v4] syscalls/mlock05: add mlock test for locking and pre-faulting of memory
Date: Thu, 9 May 2024 16:49:20 +0200 [thread overview]
Message-ID: <ZjzicK0BunOFmjHn@yuki> (raw)
In-Reply-To: <20240509133712.3383293-1-fstornio@redhat.com>
Hi!
> +static unsigned long get_proc_smaps_field(unsigned long desired_mapping_address, char *desired_field)
> +{
> + bool mapping_found = false;
> + char buffer[LINELEN] = "";
> + FILE *file = NULL;
> + int ret = 0;
There is no point in initializing buffer, file and ret these are written
to before we use the value.
> + file = fopen("/proc/self/smaps", "r");
> + if (file == NULL) {
> + tst_brk(TBROK | TERRNO, "cannot open file proc/self/smaps");
> + return 0;
> + }
Use SAFE_FOPEN() please.
> + // find desired mapping
> + while (fgets(buffer, LINELEN, file) != NULL) {
> + unsigned long mapping_address;
> +
> + // check the starting address
I do not find this comment to be useful, we do have a rule in LTP not to
comment obvious and I would argue that this comment does so.
> + ret = sscanf(buffer, "%lx[^-]", &mapping_address);
> +
> + if ((ret == 1) && (mapping_address == desired_mapping_address)) {
> + mapping_found = true;
> + break;
> + }
> + }
> +
> + if (!mapping_found) {
> + fclose(file);
SAFE_FCLOSE() please and in the rest of the cases below.
> + tst_brk(TBROK, "cannot find mapping %lx in proc/self/smaps", desired_mapping_address);
> + return 0;
> + }
> +
> + // find desired field
> + while (fgets(buffer, LINELEN, file) != NULL) {
> + if (strstr(buffer, desired_field) != NULL) {
Can we use strncmp() to match the prefix rather a substring? At the
moment "Locked" and "Rss" are not substrings of other keys in that file
but that may change at some point.
> + unsigned long desired_value;
> +
> + // extract the value for the requested field
Here as well, commenting the obvious.
> + ret = sscanf(buffer, "%*[^0-9]%lu%*[^0-9]", &desired_value);
The key value is divided by : and thge entries we are interested in are
in kB so "%*[^:]%lu kB" should be a bit safer.
> + fclose(file);
> +
> + if (ret != 1) {
> + tst_brk(TBROK, "failure occured while reading field %s", desired_field);
> + return 0;
> + }
> +
> + return desired_value;
> + }
> + }
> +
> + fclose(file);
> + tst_brk(TBROK, "cannot find %s field", desired_field);
> +
> + return 0;
> +}
> +
> +static void verify_mlock(void)
> +{
> + unsigned long Locked;
> + unsigned long Rss;
> + char *buf;
> +
> + buf = SAFE_MMAP(NULL, MMAPLEN, PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
> + SAFE_MLOCK(buf, MMAPLEN);
> +
> + Rss = get_proc_smaps_field((unsigned long)buf, "Rss");
> + Locked = get_proc_smaps_field((unsigned long)buf, "Locked");
Hmm, we do parse the whole file twice here, just the get to a nearly
same line. Why can't we just point two pointrs to unsigned long to the
function and collect both while we read the file?
> + // Convertion from KiB to B
> + Rss *= 1024;
> + Locked *= 1024;
> +
> + TST_EXP_EQ_LU(Rss, MMAPLEN);
> + TST_EXP_EQ_LU(Locked, MMAPLEN);
> +
> + SAFE_MUNLOCK(buf, MMAPLEN);
> + SAFE_MUNMAP(buf, MMAPLEN);
> +}
> +
> +static struct tst_test test = {
> + .test_all = verify_mlock,
> +};
--
Cyril Hrubis
chrubis@suse.cz
--
Mailing list info: https://lists.linux.it/listinfo/ltp
prev parent reply other threads:[~2024-05-09 14:50 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-09 13:37 [LTP] [PATCH v4] syscalls/mlock05: add mlock test for locking and pre-faulting of memory Filippo Storniolo
2024-05-09 14:49 ` Cyril Hrubis [this message]
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