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([94.75.70.14]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a7516310768sm269306866b.218.2024.07.02.04.01.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Jul 2024 04:01:41 -0700 (PDT) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 778ebf9e-3862-11ef-92e8-0d9d20120eaa DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1719918102; x=1720522902; darn=lists.xenproject.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=hqKpyboE7tWF7PWd9CeoA+EhM5ccJlbOY2elCP5bC/s=; b=eDKl2TfKYuNYR3VkgCIG/TlcMlGiaxVmlAffgk233KnErFKiKTAGVWfbsv+1o/Zlcc 02X7c1MTsYiAeyahRy3g1twZd9IrbQ0Fpl5xafmJ1e3o0JkKR623pP1lj/QY3/1/En0R KAK4KomBgvSwJdRA692YLGqmRxIma9WWxWs/CCAVPdXh0cMkYpY+OyxlHZpBhpj50SXx tweWqlUTJw6/XitD7ZXGMqLsPu36arUAdNSGGFdZ6VMByjGNivjzGIK1ltYfsltKaaTg I9f3njKTerrzAvFcNemmcwrtOAFa72iDJdWKFijIPyLoVa2RKCIF/WQtWLeTW4BDLoYJ OFtg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1719918102; x=1720522902; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=hqKpyboE7tWF7PWd9CeoA+EhM5ccJlbOY2elCP5bC/s=; b=uhiFKxnDJLKbDid97eH27qmB1yJemhqFbtAAhnvxzhZb6fE3zNXBSSZH6CDBh2+D1o Xn6WEJJTIa5TMGmJqBMVblxdBFObU8El7ERHsYtXxUlCksMlB66JXFq/GWDi1ehHLX93 4wCdfKhOHWzXJ3HeQi8wj6zw8QD747t9wZFzXbf5Eln6zvo532mWAovK/rTeDNj7I5U9 jBfIla75MpHG2HBJeh9s6p5icoJMzSF5vTZYuukJkBSQRwj2qJVD0E53E6voIMUOERKd G4bop1mN78fCsmyTkqvchQGKdIdfYKEX15o+iS7WDuiVDdzH6uJ0OCAPVKD1MMRB3pVO iUWQ== X-Gm-Message-State: AOJu0YydP7BLoiR9CsofGCbaj+hB2aAsieMyYuTbiWFWd7W4InxY+ZNW nvdQh7n+cFND/EgXemuG3f0NrOeKT6mL+dj9zcavlUEC4Cg9OBPd9nPQY2wu X-Google-Smtp-Source: AGHT+IG8tPIWzmPpWKtRBU14f4lxe94t3/47nhTs//yLUzC01QZ4fu+LclromPDoQq9XdS/FnnUnIA== X-Received: by 2002:a05:6512:1246:b0:52c:8024:1db with SMTP id 2adb3069b0e04-52e827364d9mr6402711e87.63.1719918101862; Tue, 02 Jul 2024 04:01:41 -0700 (PDT) From: Oleksii Kurochko To: xen-devel@lists.xenproject.org Cc: Oleksii Kurochko , Stefano Stabellini , Julien Grall , Bertrand Marquis , Michal Orzel , Volodymyr Babchuk , Andrew Cooper , Jan Beulich , Shawn Anastasio , =?utf-8?q?Roger_Pau_Mon?= =?utf-8?q?n=C3=A9?= Subject: [PATCH v14 1/9] xen: introduce generic non-atomic test_*bit() Date: Tue, 2 Jul 2024 13:01:28 +0200 Message-ID: <2f60d1fd7b3ac7d603486ce03a112d58352bf16d.1719917348.git.oleksii.kurochko@gmail.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: References: MIME-Version: 1.0 The following generic functions were introduced: * test_bit * generic__test_and_set_bit * generic__test_and_clear_bit * generic__test_and_change_bit These functions and macros can be useful for architectures that don't have corresponding arch-specific instructions. Also, the patch introduces the following generics which are used by the functions mentioned above: * BITOP_BITS_PER_WORD * BITOP_MASK * BITOP_WORD * BITOP_TYPE The following approach was chosen for generic*() and arch*() bit operation functions: If the bit operation function that is going to be generic starts with the prefix "__", then the corresponding generic/arch function will also contain the "__" prefix. For example: * test_bit() will be defined using arch_test_bit() and generic_test_bit(). * __test_and_set_bit() will be defined using arch__test_and_set_bit() and generic__test_and_set_bit(). Signed-off-by: Oleksii Kurochko Reviewed-by: Jan Beulich Reviewed-by: Michal Orzel --- Changes in V14: - Nothing changed. Only Rebase. --- Changes in V13: - add Reviewed-by: Jan Beulich --- Changes in V12: - revert change of moving the definition of BITS_PER_BYTE from /bitops.h to xen/bitops.h. ( a separate patch will be provided to put BITS_PER_BYTE to proper place ) - drop comments on top of generic_*() functions and update the comments above __test_*() and test_bit(). - update how static inline __test_*() are defined ( drop pointless fallback #define ) and test_bit(). - drop the footer after Signed-off-by. Changes in V11: - fix identation in generic_test_bit() function. - move definition of BITS_PER_BYTE from /bitops.h to xen/bitops.h - drop the changes in arm64/livepatch.c. - update the the comments on top of functions: generic__test_and_set_bit(), generic__test_and_clear_bit(), generic__test_and_change_bit(), generic_test_bit(). - Update footer after Signed-off section. - Rebase the patch on top of staging branch, so it can be merged when necessary approves will be given. - add Reviewed-by: Jan Beulich . --- Changes in V10: - update the commit message. ( re-order paragraphs and add explanation usage of prefix "__" in bit operation function names ) - add parentheses around the whole expression of bitop_bad_size() macros. - move macros bitop_bad_size() above asm/bitops.h as it is not arch-specific anymore and there is no need for overriding it. - drop macros check_bitop_size() and use "if ( bitop_bad_size(addr) ) __bitop_bad_size();" implictly where it is needed. - in use 'int' as a first parameter for __test_and_*(), generic__test_and_*() to be consistent with how the mentioned functions were declared in the original per-arch functions. - add 'const' to p variable in generic_test_bit(). - move definition of BITOP_BITS_PER_WORD and bitop_uint_t to xen/bitops.h as we don't allow for arch overrides these definitions anymore. --- Changes in V9: - move up xen/bitops.h in ppc/asm/page.h. - update defintion of arch_check_bitop_size. And drop correspondent macros from x86/asm/bitops.h - drop parentheses in generic__test_and_set_bit() for definition of local variable p. - fix indentation inside #ifndef BITOP_TYPE...#endif - update the commit message. --- Changes in V8: - drop __pure for function which uses volatile. - drop unnessary () in generic__test_and_change_bit() for addr casting. - update prototype of generic_test_bit() and test_bit(): now it returns bool instead of int. - update generic_test_bit() to use BITOP_MASK(). - Deal with fls{l} changes: it should be in the patch with introduced generic fls{l}. - add a footer with explanation of dependency on an uncommitted patch after Signed-off. - abstract bitop_size(). - move BITOP_TYPE define to . --- Changes in V7: - move everything to xen/bitops.h to follow the same approach for all generic bit ops. - put together BITOP_BITS_PER_WORD and bitops_uint_t. - make BITOP_MASK more generic. - drop #ifdef ... #endif around BITOP_MASK, BITOP_WORD as they are generic enough. - drop "_" for generic__{test_and_set_bit,...}(). - drop " != 0" for functions which return bool. - add volatile during the cast for generic__{...}(). - update the commit message. - update arch related code to follow the proposed generic approach. --- Changes in V6: - Nothing changed ( only rebase ) --- Changes in V5: - new patch --- xen/arch/arm/include/asm/bitops.h | 69 ----------- xen/arch/ppc/include/asm/bitops.h | 54 --------- xen/arch/ppc/include/asm/page.h | 2 +- xen/arch/ppc/mm-radix.c | 2 +- xen/arch/x86/include/asm/bitops.h | 31 ++--- xen/include/xen/bitops.h | 182 ++++++++++++++++++++++++++++++ 6 files changed, 193 insertions(+), 147 deletions(-) diff --git a/xen/arch/arm/include/asm/bitops.h b/xen/arch/arm/include/asm/bitops.h index 8f4bdc09d1..db23d7edc3 100644 --- a/xen/arch/arm/include/asm/bitops.h +++ b/xen/arch/arm/include/asm/bitops.h @@ -22,11 +22,6 @@ #define __set_bit(n,p) set_bit(n,p) #define __clear_bit(n,p) clear_bit(n,p) -#define BITOP_BITS_PER_WORD 32 -#define BITOP_MASK(nr) (1UL << ((nr) % BITOP_BITS_PER_WORD)) -#define BITOP_WORD(nr) ((nr) / BITOP_BITS_PER_WORD) -#define BITS_PER_BYTE 8 - #define ADDR (*(volatile int *) addr) #define CONST_ADDR (*(const volatile int *) addr) @@ -76,70 +71,6 @@ bool test_and_change_bit_timeout(int nr, volatile void *p, bool clear_mask16_timeout(uint16_t mask, volatile void *p, unsigned int max_try); -/** - * __test_and_set_bit - Set a bit and return its old value - * @nr: Bit to set - * @addr: Address to count from - * - * This operation is non-atomic and can be reordered. - * If two examples of this operation race, one can appear to succeed - * but actually fail. You must protect multiple accesses with a lock. - */ -static inline int __test_and_set_bit(int nr, volatile void *addr) -{ - unsigned int mask = BITOP_MASK(nr); - volatile unsigned int *p = - ((volatile unsigned int *)addr) + BITOP_WORD(nr); - unsigned int old = *p; - - *p = old | mask; - return (old & mask) != 0; -} - -/** - * __test_and_clear_bit - Clear a bit and return its old value - * @nr: Bit to clear - * @addr: Address to count from - * - * This operation is non-atomic and can be reordered. - * If two examples of this operation race, one can appear to succeed - * but actually fail. You must protect multiple accesses with a lock. - */ -static inline int __test_and_clear_bit(int nr, volatile void *addr) -{ - unsigned int mask = BITOP_MASK(nr); - volatile unsigned int *p = - ((volatile unsigned int *)addr) + BITOP_WORD(nr); - unsigned int old = *p; - - *p = old & ~mask; - return (old & mask) != 0; -} - -/* WARNING: non atomic and it can be reordered! */ -static inline int __test_and_change_bit(int nr, - volatile void *addr) -{ - unsigned int mask = BITOP_MASK(nr); - volatile unsigned int *p = - ((volatile unsigned int *)addr) + BITOP_WORD(nr); - unsigned int old = *p; - - *p = old ^ mask; - return (old & mask) != 0; -} - -/** - * test_bit - Determine whether a bit is set - * @nr: bit number to test - * @addr: Address to start counting from - */ -static inline int test_bit(int nr, const volatile void *addr) -{ - const volatile unsigned int *p = (const volatile unsigned int *)addr; - return 1UL & (p[BITOP_WORD(nr)] >> (nr & (BITOP_BITS_PER_WORD-1))); -} - #define arch_ffs(x) ((x) ? 1 + __builtin_ctz(x) : 0) #define arch_ffsl(x) ((x) ? 1 + __builtin_ctzl(x) : 0) #define arch_fls(x) ((x) ? 32 - __builtin_clz(x) : 0) diff --git a/xen/arch/ppc/include/asm/bitops.h b/xen/arch/ppc/include/asm/bitops.h index 8119b5ace8..ee0e58e2e8 100644 --- a/xen/arch/ppc/include/asm/bitops.h +++ b/xen/arch/ppc/include/asm/bitops.h @@ -15,11 +15,6 @@ #define __set_bit(n, p) set_bit(n, p) #define __clear_bit(n, p) clear_bit(n, p) -#define BITOP_BITS_PER_WORD 32 -#define BITOP_MASK(nr) (1U << ((nr) % BITOP_BITS_PER_WORD)) -#define BITOP_WORD(nr) ((nr) / BITOP_BITS_PER_WORD) -#define BITS_PER_BYTE 8 - /* PPC bit number conversion */ #define PPC_BITLSHIFT(be) (BITS_PER_LONG - 1 - (be)) #define PPC_BIT(bit) (1UL << PPC_BITLSHIFT(bit)) @@ -69,17 +64,6 @@ static inline void clear_bit(int nr, volatile void *addr) clear_bits(BITOP_MASK(nr), (volatile unsigned int *)addr + BITOP_WORD(nr)); } -/** - * test_bit - Determine whether a bit is set - * @nr: bit number to test - * @addr: Address to start counting from - */ -static inline int test_bit(int nr, const volatile void *addr) -{ - const volatile unsigned int *p = addr; - return 1 & (p[BITOP_WORD(nr)] >> (nr & (BITOP_BITS_PER_WORD - 1))); -} - static inline unsigned int test_and_clear_bits( unsigned int mask, volatile unsigned int *p) @@ -133,44 +117,6 @@ static inline int test_and_set_bit(unsigned int nr, volatile void *addr) (volatile unsigned int *)addr + BITOP_WORD(nr)) != 0; } -/** - * __test_and_set_bit - Set a bit and return its old value - * @nr: Bit to set - * @addr: Address to count from - * - * This operation is non-atomic and can be reordered. - * If two examples of this operation race, one can appear to succeed - * but actually fail. You must protect multiple accesses with a lock. - */ -static inline int __test_and_set_bit(int nr, volatile void *addr) -{ - unsigned int mask = BITOP_MASK(nr); - volatile unsigned int *p = (volatile unsigned int *)addr + BITOP_WORD(nr); - unsigned int old = *p; - - *p = old | mask; - return (old & mask) != 0; -} - -/** - * __test_and_clear_bit - Clear a bit and return its old value - * @nr: Bit to clear - * @addr: Address to count from - * - * This operation is non-atomic and can be reordered. - * If two examples of this operation race, one can appear to succeed - * but actually fail. You must protect multiple accesses with a lock. - */ -static inline int __test_and_clear_bit(int nr, volatile void *addr) -{ - unsigned int mask = BITOP_MASK(nr); - volatile unsigned int *p = (volatile unsigned int *)addr + BITOP_WORD(nr); - unsigned int old = *p; - - *p = old & ~mask; - return (old & mask) != 0; -} - #define arch_ffs(x) ((x) ? 1 + __builtin_ctz(x) : 0) #define arch_ffsl(x) ((x) ? 1 + __builtin_ctzl(x) : 0) #define arch_fls(x) ((x) ? 32 - __builtin_clz(x) : 0) diff --git a/xen/arch/ppc/include/asm/page.h b/xen/arch/ppc/include/asm/page.h index 890e285051..6d4cd2611c 100644 --- a/xen/arch/ppc/include/asm/page.h +++ b/xen/arch/ppc/include/asm/page.h @@ -2,9 +2,9 @@ #ifndef _ASM_PPC_PAGE_H #define _ASM_PPC_PAGE_H +#include #include -#include #include #define PDE_VALID PPC_BIT(0) diff --git a/xen/arch/ppc/mm-radix.c b/xen/arch/ppc/mm-radix.c index ab5a10695c..9055730997 100644 --- a/xen/arch/ppc/mm-radix.c +++ b/xen/arch/ppc/mm-radix.c @@ -1,11 +1,11 @@ /* SPDX-License-Identifier: GPL-2.0-or-later */ +#include #include #include #include #include #include -#include #include #include #include diff --git a/xen/arch/x86/include/asm/bitops.h b/xen/arch/x86/include/asm/bitops.h index aa71542e7b..f9aa60111f 100644 --- a/xen/arch/x86/include/asm/bitops.h +++ b/xen/arch/x86/include/asm/bitops.h @@ -19,9 +19,6 @@ #define ADDR (*(volatile int *) addr) #define CONST_ADDR (*(const volatile int *) addr) -extern void __bitop_bad_size(void); -#define bitop_bad_size(addr) (sizeof(*(addr)) < 4) - /** * set_bit - Atomically set a bit in memory * @nr: the bit to set @@ -175,7 +172,7 @@ static inline int test_and_set_bit(int nr, volatile void *addr) }) /** - * __test_and_set_bit - Set a bit and return its old value + * arch__test_and_set_bit - Set a bit and return its old value * @nr: Bit to set * @addr: Address to count from * @@ -183,7 +180,7 @@ static inline int test_and_set_bit(int nr, volatile void *addr) * If two examples of this operation race, one can appear to succeed * but actually fail. You must protect multiple accesses with a lock. */ -static inline int __test_and_set_bit(int nr, void *addr) +static inline int arch__test_and_set_bit(int nr, volatile void *addr) { int oldbit; @@ -194,10 +191,7 @@ static inline int __test_and_set_bit(int nr, void *addr) return oldbit; } -#define __test_and_set_bit(nr, addr) ({ \ - if ( bitop_bad_size(addr) ) __bitop_bad_size(); \ - __test_and_set_bit(nr, addr); \ -}) +#define arch__test_and_set_bit arch__test_and_set_bit /** * test_and_clear_bit - Clear a bit and return its old value @@ -224,7 +218,7 @@ static inline int test_and_clear_bit(int nr, volatile void *addr) }) /** - * __test_and_clear_bit - Clear a bit and return its old value + * arch__test_and_clear_bit - Clear a bit and return its old value * @nr: Bit to set * @addr: Address to count from * @@ -232,7 +226,7 @@ static inline int test_and_clear_bit(int nr, volatile void *addr) * If two examples of this operation race, one can appear to succeed * but actually fail. You must protect multiple accesses with a lock. */ -static inline int __test_and_clear_bit(int nr, void *addr) +static inline int arch__test_and_clear_bit(int nr, volatile void *addr) { int oldbit; @@ -243,13 +237,10 @@ static inline int __test_and_clear_bit(int nr, void *addr) return oldbit; } -#define __test_and_clear_bit(nr, addr) ({ \ - if ( bitop_bad_size(addr) ) __bitop_bad_size(); \ - __test_and_clear_bit(nr, addr); \ -}) +#define arch__test_and_clear_bit arch__test_and_clear_bit /* WARNING: non atomic and it can be reordered! */ -static inline int __test_and_change_bit(int nr, void *addr) +static inline int arch__test_and_change_bit(int nr, volatile void *addr) { int oldbit; @@ -260,10 +251,7 @@ static inline int __test_and_change_bit(int nr, void *addr) return oldbit; } -#define __test_and_change_bit(nr, addr) ({ \ - if ( bitop_bad_size(addr) ) __bitop_bad_size(); \ - __test_and_change_bit(nr, addr); \ -}) +#define arch__test_and_change_bit arch__test_and_change_bit /** * test_and_change_bit - Change a bit and return its new value @@ -307,8 +295,7 @@ static inline int variable_test_bit(int nr, const volatile void *addr) return oldbit; } -#define test_bit(nr, addr) ({ \ - if ( bitop_bad_size(addr) ) __bitop_bad_size(); \ +#define arch_test_bit(nr, addr) ({ \ __builtin_constant_p(nr) ? \ constant_test_bit(nr, addr) : \ variable_test_bit(nr, addr); \ diff --git a/xen/include/xen/bitops.h b/xen/include/xen/bitops.h index 6a5e28730a..cc09d273c9 100644 --- a/xen/include/xen/bitops.h +++ b/xen/include/xen/bitops.h @@ -4,6 +4,19 @@ #include #include +#define BITOP_BITS_PER_WORD 32 +typedef uint32_t bitop_uint_t; + +#define BITOP_MASK(nr) ((bitop_uint_t)1 << ((nr) % BITOP_BITS_PER_WORD)) + +#define BITOP_WORD(nr) ((nr) / BITOP_BITS_PER_WORD) + +#define BITS_PER_BYTE 8 + +extern void __bitop_bad_size(void); + +#define bitop_bad_size(addr) (sizeof(*(addr)) < sizeof(bitop_uint_t)) + #include /* @@ -24,6 +37,175 @@ unsigned int __pure generic_ffsl(unsigned long x); unsigned int __pure generic_flsl(unsigned long x); +/** + * generic__test_and_set_bit - Set a bit and return its old value + * @nr: Bit to set + * @addr: Address to count from + * + * This operation is non-atomic and can be reordered. + * If two examples of this operation race, one can appear to succeed + * but actually fail. You must protect multiple accesses with a lock. + */ +static always_inline bool +generic__test_and_set_bit(int nr, volatile void *addr) +{ + bitop_uint_t mask = BITOP_MASK(nr); + volatile bitop_uint_t *p = (volatile bitop_uint_t *)addr + BITOP_WORD(nr); + bitop_uint_t old = *p; + + *p = old | mask; + return (old & mask); +} + +/** + * generic__test_and_clear_bit - Clear a bit and return its old value + * @nr: Bit to clear + * @addr: Address to count from + * + * This operation is non-atomic and can be reordered. + * If two examples of this operation race, one can appear to succeed + * but actually fail. You must protect multiple accesses with a lock. + */ +static always_inline bool +generic__test_and_clear_bit(int nr, volatile void *addr) +{ + bitop_uint_t mask = BITOP_MASK(nr); + volatile bitop_uint_t *p = (volatile bitop_uint_t *)addr + BITOP_WORD(nr); + bitop_uint_t old = *p; + + *p = old & ~mask; + return (old & mask); +} + +/** + * generic__test_and_change_bit - Change a bit and return its old value + * @nr: Bit to change + * @addr: Address to count from + * + * This operation is non-atomic and can be reordered. + * If two examples of this operation race, one can appear to succeed + * but actually fail. You must protect multiple accesses with a lock. + */ +static always_inline bool +generic__test_and_change_bit(int nr, volatile void *addr) +{ + bitop_uint_t mask = BITOP_MASK(nr); + volatile bitop_uint_t *p = (volatile bitop_uint_t *)addr + BITOP_WORD(nr); + bitop_uint_t old = *p; + + *p = old ^ mask; + return (old & mask); +} + +/** + * generic_test_bit - Determine whether a bit is set + * @nr: bit number to test + * @addr: Address to start counting from + * + * This operation is non-atomic and can be reordered. + * If two examples of this operation race, one can appear to succeed + * but actually fail. You must protect multiple accesses with a lock. + */ +static always_inline bool generic_test_bit(int nr, const volatile void *addr) +{ + bitop_uint_t mask = BITOP_MASK(nr); + const volatile bitop_uint_t *p = + (const volatile bitop_uint_t *)addr + BITOP_WORD(nr); + + return (*p & mask); +} + +/** + * __test_and_set_bit - Set a bit and return its old value + * @nr: Bit to set + * @addr: Address to count from + * + * This operation is non-atomic and can be reordered. + * If two examples of this operation race, one can appear to succeed + * but actually fail. You must protect multiple accesses with a lock. + */ +static always_inline bool +__test_and_set_bit(int nr, volatile void *addr) +{ +#ifndef arch__test_and_set_bit +#define arch__test_and_set_bit generic__test_and_set_bit +#endif + + return arch__test_and_set_bit(nr, addr); +} +#define __test_and_set_bit(nr, addr) ({ \ + if ( bitop_bad_size(addr) ) __bitop_bad_size(); \ + __test_and_set_bit(nr, addr); \ +}) + +/** + * __test_and_clear_bit - Clear a bit and return its old value + * @nr: Bit to clear + * @addr: Address to count from + * + * This operation is non-atomic and can be reordered. + * If two examples of this operation race, one can appear to succeed + * but actually fail. You must protect multiple accesses with a lock. + */ +static always_inline bool +__test_and_clear_bit(int nr, volatile void *addr) +{ +#ifndef arch__test_and_clear_bit +#define arch__test_and_clear_bit generic__test_and_clear_bit +#endif + + return arch__test_and_clear_bit(nr, addr); +} +#define __test_and_clear_bit(nr, addr) ({ \ + if ( bitop_bad_size(addr) ) __bitop_bad_size(); \ + __test_and_clear_bit(nr, addr); \ +}) + +/** + * __test_and_change_bit - Change a bit and return its old value + * @nr: Bit to change + * @addr: Address to count from + * + * This operation is non-atomic and can be reordered. + * If two examples of this operation race, one can appear to succeed + * but actually fail. You must protect multiple accesses with a lock. + */ +static always_inline bool +__test_and_change_bit(int nr, volatile void *addr) +{ +#ifndef arch__test_and_change_bit +#define arch__test_and_change_bit generic__test_and_change_bit +#endif + + return arch__test_and_change_bit(nr, addr); +} +#define __test_and_change_bit(nr, addr) ({ \ + if ( bitop_bad_size(addr) ) __bitop_bad_size(); \ + __test_and_change_bit(nr, addr); \ +}) + +/** + * test_bit - Determine whether a bit is set + * @nr: bit number to test + * @addr: Address to start counting from + * + * This operation is non-atomic and can be reordered. + * If two examples of this operation race, one can appear to succeed + * but actually fail. You must protect multiple accesses with a lock. + */ +static always_inline bool test_bit(int nr, const volatile void *addr) +{ +#ifndef arch_test_bit +#define arch_test_bit generic_test_bit +#endif + + return arch_test_bit(nr, addr); +} +#define test_bit(nr, addr) ({ \ + if ( bitop_bad_size(addr) ) __bitop_bad_size(); \ + test_bit(nr, addr); \ +}) + static always_inline __pure unsigned int ffs(unsigned int x) { if ( __builtin_constant_p(x) )