Re: [LTP] [PATCH v4 1/7] libltpswap: Add tst_max_swapfiles api

[Petr Vorel <pvorel@suse.cz>]

Hi Yang Xu,

Reviewed-by: Petr Vorel <pvorel@suse.cz>
generally LGTM, just minor things below.

nit in subject: s/api/API/

> Current, the kernel constant MAX_SWAPFILES value is calculated as below
nit: I'm not a native speaker, but:
s/Current/Currently/

> ------------------------------------
> //#ifdef CONFIG_DEVICE_PRIVATE
> //#define SWP_DEVICE_NUM 4
> //#else
> //#define SWP_DEVICE_NUM 0
> //#endif

> //#ifdef CONFIG_MIGRATION
> //#define SWP_MIGRATION_NUM 3
> //#else
> //#define SWP_MIGRATION_NUM 0

> //#ifdef CONFIG_MEMORY_FAILURE
> //#define SWP_HWPOISON_NUM 1
> //#else
> //#define SWP_HWPOISON_NUM 0
> //#endif

> //#define SWP_PTE_MARKER_NUM 1
> //#define MAX_SWAPFILES_SHIFT   5

> //#define MAX_SWAPFILES \
> //      ((1 << MAX_SWAPFILES_SHIFT) - SWP_DEVICE_NUM - \
> //      SWP_MIGRATION_NUM - SWP_HWPOISON_NUM - \
> //      SWP_PTE_MARKER_NUM)

nit: if you indent this code with space or tab it will be visible without //.
Using // makes text harder to read.

> ------------------------------------
> Also, man-pages missed something after 5.14 kernel. I have sent two patches[1][2] to
> add it. The kernel patches modify this kernel constant in[3][4][5][6]. Also, after kernel 6.2.0
> [7],kernel always compile in pte markers.

> [1]https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/commit/?id=26f3ec74e
> [2]https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/commit/?id=6bf3937fc
> [3]https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/include/linux/swap.h?id=5042db43cc
> [4]https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/include/linux/swap.h?id=b756a3b5e
> [5]https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/include/linux/swap.h?id=679d10331
> [6]https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/include/linux/swap.h?id=6c287605f
> [7]https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/include/linux/swap.h?id=ca92ea3dc5

> Signed-off-by: Yang Xu <xuyang2018.jy@fujitsu.com>
> ---
>  include/libswap.h         |  6 +++++
>  libs/libltpswap/libswap.c | 48 +++++++++++++++++++++++++++++++++++++++
>  2 files changed, 54 insertions(+)

> diff --git a/include/libswap.h b/include/libswap.h
> index bdc5aacc6..361d73175 100644
> --- a/include/libswap.h
> +++ b/include/libswap.h
> @@ -21,4 +21,10 @@ int make_swapfile(const char *swapfile, int blocks, int safe);
>   * we are testing on.
>   */
>  bool is_swap_supported(const char *filename);
> +
> +/*
> + * Get kernel constant MAX_SWAPFILES value
nit: . at the end.

> + */
> +int tst_max_swapfiles(void);
> +
>  #endif /* __LIBSWAP_H__ */
> diff --git a/libs/libltpswap/libswap.c b/libs/libltpswap/libswap.c
> index c79de19d7..a404a4ada 100644
> --- a/libs/libltpswap/libswap.c
> +++ b/libs/libltpswap/libswap.c
> @@ -16,6 +16,8 @@
>  #include "tst_test.h"
>  #include "libswap.h"
>  #include "lapi/syscalls.h"
> +#include "tst_kconfig.h"
> +#include "tst_safe_stdio.h"

>  static const char *const swap_supported_fs[] = {
>  	"btrfs",
> @@ -217,3 +219,49 @@ bool is_swap_supported(const char *filename)

>  	return true;
>  }
> +
> +/*
> + * Get kernel constant MAX_SWAPFILES value
nit: . at the end.

> + */
> +int tst_max_swapfiles(void)
> +{
> +	unsigned int max_swapfile = 32;
nit never change, maybe
#define DEFAULT_MAX_SWAPFILE 32

> +	unsigned int swp_migration_num = 0, swp_hwpoison_num = 0, swp_device_num = 0, swp_pte_marker_num = 0;
nit: very long line maybe split (readability):
	unsigned int swp_migration_num = 0, swp_hwpoison_num = 0,
		     swp_device_num = 0, swp_pte_marker_num = 0;

But file is full of ugly lines, feel free to ignore.

> +	struct tst_kconfig_var migration_kconfig = TST_KCONFIG_INIT("CONFIG_MIGRATION");
> +	struct tst_kconfig_var memory_kconfig = TST_KCONFIG_INIT("CONFIG_MEMORY_FAILURE");
> +	struct tst_kconfig_var device_kconfig = TST_KCONFIG_INIT("CONFIG_DEVICE_PRIVATE");
> +	struct tst_kconfig_var marker_kconfig = TST_KCONFIG_INIT("CONFIG_PTE_MARKER");
Maybe shorten variable - remove "_kconfig" (obvious from use by .choice member).

> +
> +	tst_kconfig_read(&migration_kconfig, 1);
> +	tst_kconfig_read(&memory_kconfig, 1);
> +	tst_kconfig_read(&device_kconfig, 1);
> +	tst_kconfig_read(&marker_kconfig, 1);
> +
> +	if (migration_kconfig.choice == 'y') {
> +		if (tst_kvercmp(5, 19, 0) < 0)
> +			swp_migration_num = 2;
> +		else
> +			swp_migration_num = 3;
> +	}
> +
> +	if (memory_kconfig.choice == 'y')
> +		swp_hwpoison_num = 1;
> +
> +	if (device_kconfig.choice == 'y') {
> +		if (tst_kvercmp(4, 14, 0) >= 0)
> +			swp_device_num = 2;
> +		if (tst_kvercmp(5, 14, 0) >= 0)
> +			swp_device_num = 4;
> +	}
> +
> +	if (tst_kvercmp(6, 2, 0) >= 0) {
> +		swp_pte_marker_num = 1;
> +	} else {
> +		if (marker_kconfig.choice == 'y') {
> +			if (tst_kvercmp(5, 19, 0) >= 0)
> +				swp_pte_marker_num = 1;
> +		}

Maybe just:

	if ((marker_kconfig.choice == 'y' && tst_kvercmp(5, 19, 0) >= 0) ||
		tst_kvercmp(6, 2, 0) >= 0) {
		swp_pte_marker_num = 1;
	}

> +	}
> +
> +	return max_swapfile - swp_migration_num - swp_hwpoison_num - swp_device_num - swp_pte_marker_num;
> +}

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