From: Vishal Verma <vishal.l.verma@intel.com> To: <linux-cxl@vger.kernel.org> Cc: Dan Williams <dan.j.williams@intel.com>, Ben Widawsky <ben.widawsky@intel.com>, <nvdimm@lists.linux.dev>, Vishal Verma <vishal.l.verma@intel.com> Subject: [ndctl PATCH v4 04/17] util: add the struct_size() helper from the kernel Date: Thu, 7 Oct 2021 02:21:26 -0600 [thread overview] Message-ID: <20211007082139.3088615-5-vishal.l.verma@intel.com> (raw) In-Reply-To: <20211007082139.3088615-1-vishal.l.verma@intel.com> Add struct_size() from include/linux/overflow.h which calculates the size of a struct with a trailing variable length array. Suggested-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Vishal Verma <vishal.l.verma@intel.com> --- util/size.h | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++++ util/util.h | 6 ++++++ 2 files changed, 68 insertions(+) diff --git a/util/size.h b/util/size.h index 646edae..a0f3593 100644 --- a/util/size.h +++ b/util/size.h @@ -4,6 +4,8 @@ #ifndef _NDCTL_SIZE_H_ #define _NDCTL_SIZE_H_ #include <stdbool.h> +#include <stdint.h> +#include <util/util.h> #define SZ_1K 0x00000400 #define SZ_4K 0x00001000 @@ -30,4 +32,64 @@ static inline bool is_power_of_2(unsigned long long v) #define BITS_PER_LONG (sizeof(unsigned long) * 8) #define HPAGE_SIZE (2 << 20) +/* + * Helpers for struct_size() copied from include/linux/overflow.h (GPL-2.0) + * + * For simplicity and code hygiene, the fallback code below insists on + * a, b and *d having the same type (similar to the min() and max() + * macros), whereas gcc's type-generic overflow checkers accept + * different types. Hence we don't just make check_add_overflow an + * alias for __builtin_add_overflow, but add type checks similar to + * below. + */ +#define check_add_overflow(a, b, d) (({ \ + typeof(a) __a = (a); \ + typeof(b) __b = (b); \ + typeof(d) __d = (d); \ + (void) (&__a == &__b); \ + (void) (&__a == __d); \ + __builtin_add_overflow(__a, __b, __d); \ +})) + +#define check_mul_overflow(a, b, d) (({ \ + typeof(a) __a = (a); \ + typeof(b) __b = (b); \ + typeof(d) __d = (d); \ + (void) (&__a == &__b); \ + (void) (&__a == __d); \ + __builtin_mul_overflow(__a, __b, __d); \ +})) + +/* + * Compute a*b+c, returning SIZE_MAX on overflow. Internal helper for + * struct_size() below. + */ +static inline size_t __ab_c_size(size_t a, size_t b, size_t c) +{ + size_t bytes; + + if (check_mul_overflow(a, b, &bytes)) + return SIZE_MAX; + if (check_add_overflow(bytes, c, &bytes)) + return SIZE_MAX; + + return bytes; +} + +/** + * struct_size() - Calculate size of structure with trailing array. + * @p: Pointer to the structure. + * @member: Name of the array member. + * @count: Number of elements in the array. + * + * Calculates size of memory needed for structure @p followed by an + * array of @count number of @member elements. + * + * Return: number of bytes needed or SIZE_MAX on overflow. + */ +#define struct_size(p, member, count) \ + __ab_c_size(count, \ + sizeof(*(p)->member) + __must_be_array((p)->member),\ + sizeof(*(p))) + #endif /* _NDCTL_SIZE_H_ */ diff --git a/util/util.h b/util/util.h index ae0e4e1..b2b4ae6 100644 --- a/util/util.h +++ b/util/util.h @@ -63,6 +63,12 @@ #define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); })) #define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)])) +/* Are two types/vars the same type (ignoring qualifiers)? */ +#define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) + +/* &a[0] degrades to a pointer: a different type from an array */ +#define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0])) + enum { READ, WRITE, }; -- 2.31.1
next prev parent reply other threads:[~2021-10-07 8:22 UTC|newest] Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-10-07 8:21 [ndctl PATCH v4 00/17] Initial CXL support Vishal Verma 2021-10-07 8:21 ` [ndctl PATCH v4 01/17] ndctl: add .clang-format Vishal Verma 2021-10-07 8:21 ` [ndctl PATCH v4 02/17] cxl: add a cxl utility and libcxl library Vishal Verma 2021-10-07 8:21 ` [ndctl PATCH v4 03/17] cxl: add a local copy of the cxl_mem UAPI header Vishal Verma 2021-10-07 8:21 ` Vishal Verma [this message] 2021-10-14 2:40 ` [ndctl PATCH v4 04/17] util: add the struct_size() helper from the kernel Dan Williams 2021-10-07 8:21 ` [ndctl PATCH v4 05/17] libcxl: add support for command query and submission Vishal Verma 2021-10-14 2:53 ` Dan Williams 2021-10-07 8:21 ` [ndctl PATCH v4 06/17] libcxl: add support for the 'Identify Device' command Vishal Verma 2021-10-07 8:21 ` [ndctl PATCH v4 07/17] libcxl: add GET_HEALTH_INFO mailbox command and accessors Vishal Verma 2021-10-14 16:01 ` Dan Williams 2021-11-02 20:22 ` Verma, Vishal L 2021-11-02 20:27 ` Dan Williams 2021-10-07 8:21 ` [ndctl PATCH v4 08/17] libcxl: add support for the 'GET_LSA' command Vishal Verma 2021-10-14 16:35 ` Dan Williams 2021-10-14 20:06 ` Verma, Vishal L 2021-10-14 20:55 ` Dan Williams 2021-10-07 8:21 ` [ndctl PATCH v4 09/17] util/hexdump: Add a util helper to print a buffer in hex Vishal Verma 2021-10-14 16:48 ` Dan Williams 2021-10-14 20:33 ` Verma, Vishal L 2021-10-14 22:39 ` Dan Williams 2021-11-02 20:25 ` Verma, Vishal L 2021-10-07 8:21 ` [ndctl PATCH v4 10/17] libcxl: add label_size to cxl_memdev, and an API to retrieve it Vishal Verma 2021-10-14 18:24 ` Dan Williams 2021-10-14 21:50 ` Verma, Vishal L 2021-10-07 8:21 ` [ndctl PATCH v4 11/17] libcxl: add a stub interface to determine whether a memdev is active Vishal Verma 2021-10-14 19:59 ` Dan Williams 2021-10-07 8:21 ` [ndctl PATCH v4 12/17] libcxl: add interfaces for label operations Vishal Verma 2021-10-14 21:27 ` Dan Williams 2021-10-14 22:18 ` Verma, Vishal L 2021-10-14 22:24 ` Verma, Vishal L 2021-10-14 22:45 ` Dan Williams 2021-10-07 8:21 ` [ndctl PATCH v4 13/17] cxl: add commands to read, write, and zero labels Vishal Verma 2021-10-14 22:34 ` Dan Williams 2021-10-07 8:21 ` [ndctl PATCH v4 14/17] Documentation/cxl: add library API documentation Vishal Verma 2021-10-14 23:31 ` Dan Williams 2021-11-05 18:58 ` Dan Williams 2021-10-07 8:21 ` [ndctl PATCH v4 15/17] ndctl: Add CXL packages to the RPM spec Vishal Verma 2021-10-14 23:33 ` Dan Williams 2021-10-07 8:21 ` [ndctl PATCH v4 16/17] cxl-cli: add bash completion Vishal Verma 2021-10-14 23:34 ` Dan Williams 2021-10-07 8:21 ` [ndctl PATCH v4 17/17] cxl: add health information to cxl-list Vishal Verma 2021-10-11 22:07 ` Verma, Vishal L 2021-10-15 0:09 ` Dan Williams 2021-10-14 23:42 ` Verma, Vishal L 2021-10-15 21:15 ` Dan Williams
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20211007082139.3088615-5-vishal.l.verma@intel.com \ --to=vishal.l.verma@intel.com \ --cc=ben.widawsky@intel.com \ --cc=dan.j.williams@intel.com \ --cc=linux-cxl@vger.kernel.org \ --cc=nvdimm@lists.linux.dev \ --subject='Re: [ndctl PATCH v4 04/17] util: add the struct_size() helper from the kernel' \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).