From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from pegase1.c-s.fr (pegase1.c-s.fr [93.17.236.30]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 41C3dK4jFNzF0kx for ; Sat, 23 Jun 2018 02:17:57 +1000 (AEST) Subject: Re: [PATCH] powerpc/mm: fix always true/false warning in slice.c To: Mathieu Malaterre Cc: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , "Aneesh Kumar K.V" , LKML , linuxppc-dev References: <63b696ab7be8b941fa1e1589f28260320d12a32a.1529589640.git.christophe.leroy@c-s.fr> From: Christophe LEROY Message-ID: <70915836-28d4-ccfb-01cc-e0c2a0251350@c-s.fr> Date: Fri, 22 Jun 2018 18:17:53 +0200 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Le 22/06/2018 à 16:55, Mathieu Malaterre a écrit : > On Fri, Jun 22, 2018 at 3:49 PM Christophe Leroy > wrote: >> >> This patch fixes the following warnings (obtained with make W=1). >> >> arch/powerpc/mm/slice.c: In function 'slice_range_to_mask': >> arch/powerpc/mm/slice.c:73:12: error: comparison is always true due to limited range of data type [-Werror=type-limits] >> if (start < SLICE_LOW_TOP) { >> ^ >> arch/powerpc/mm/slice.c:81:20: error: comparison is always false due to limited range of data type [-Werror=type-limits] >> if ((start + len) > SLICE_LOW_TOP) { >> ^ >> arch/powerpc/mm/slice.c: In function 'slice_mask_for_free': >> arch/powerpc/mm/slice.c:136:17: error: comparison is always true due to limited range of data type [-Werror=type-limits] >> if (high_limit <= SLICE_LOW_TOP) >> ^ >> arch/powerpc/mm/slice.c: In function 'slice_check_range_fits': >> arch/powerpc/mm/slice.c:185:12: error: comparison is always true due to limited range of data type [-Werror=type-limits] >> if (start < SLICE_LOW_TOP) { >> ^ >> arch/powerpc/mm/slice.c:195:39: error: comparison is always false due to limited range of data type [-Werror=type-limits] >> if (SLICE_NUM_HIGH && ((start + len) > SLICE_LOW_TOP)) { >> ^ >> arch/powerpc/mm/slice.c: In function 'slice_scan_available': >> arch/powerpc/mm/slice.c:306:11: error: comparison is always true due to limited range of data type [-Werror=type-limits] >> if (addr < SLICE_LOW_TOP) { >> ^ >> arch/powerpc/mm/slice.c: In function 'get_slice_psize': >> arch/powerpc/mm/slice.c:709:11: error: comparison is always true due to limited range of data type [-Werror=type-limits] >> if (addr < SLICE_LOW_TOP) { >> ^ >> >> Signed-off-by: Christophe Leroy >> --- >> arch/powerpc/mm/slice.c | 21 ++++++++++++++------- >> 1 file changed, 14 insertions(+), 7 deletions(-) >> >> diff --git a/arch/powerpc/mm/slice.c b/arch/powerpc/mm/slice.c >> index 9530c6db406a..17c57760e06c 100644 >> --- a/arch/powerpc/mm/slice.c >> +++ b/arch/powerpc/mm/slice.c >> @@ -62,6 +62,13 @@ static void slice_print_mask(const char *label, const struct slice_mask *mask) { >> >> #endif >> >> +static inline bool slice_addr_is_low(unsigned long addr) >> +{ >> + u64 tmp = (u64)addr; >> + >> + return tmp < SLICE_LOW_TOP; >> +} >> + >> static void slice_range_to_mask(unsigned long start, unsigned long len, >> struct slice_mask *ret) >> { >> @@ -71,7 +78,7 @@ static void slice_range_to_mask(unsigned long start, unsigned long len, >> if (SLICE_NUM_HIGH) >> bitmap_zero(ret->high_slices, SLICE_NUM_HIGH); >> >> - if (start < SLICE_LOW_TOP) { >> + if (slice_addr_is_low(start)) { >> unsigned long mend = min(end, >> (unsigned long)(SLICE_LOW_TOP - 1)); >> >> @@ -79,7 +86,7 @@ static void slice_range_to_mask(unsigned long start, unsigned long len, >> - (1u << GET_LOW_SLICE_INDEX(start)); >> } >> >> - if ((start + len) > SLICE_LOW_TOP) { >> + if (!slice_addr_is_low(end)) { >> unsigned long start_index = GET_HIGH_SLICE_INDEX(start); >> unsigned long align_end = ALIGN(end, (1UL << SLICE_HIGH_SHIFT)); >> unsigned long count = GET_HIGH_SLICE_INDEX(align_end) - start_index; >> @@ -134,7 +141,7 @@ static void slice_mask_for_free(struct mm_struct *mm, struct slice_mask *ret, >> if (!slice_low_has_vma(mm, i)) >> ret->low_slices |= 1u << i; >> >> - if (high_limit <= SLICE_LOW_TOP) >> + if (slice_addr_is_low(high_limit - 1)) > > Is high_limit ever going to be 0 ? See slice_get_unmapped_area(), high_limit will never be 0. Christophe > >> return; >> >> for (i = 0; i < GET_HIGH_SLICE_INDEX(high_limit); i++) >> @@ -183,7 +190,7 @@ static bool slice_check_range_fits(struct mm_struct *mm, >> unsigned long end = start + len - 1; >> u64 low_slices = 0; >> >> - if (start < SLICE_LOW_TOP) { >> + if (slice_addr_is_low(start)) { >> unsigned long mend = min(end, >> (unsigned long)(SLICE_LOW_TOP - 1)); >> >> @@ -193,7 +200,7 @@ static bool slice_check_range_fits(struct mm_struct *mm, >> if ((low_slices & available->low_slices) != low_slices) >> return false; >> >> - if (SLICE_NUM_HIGH && ((start + len) > SLICE_LOW_TOP)) { >> + if (SLICE_NUM_HIGH && !slice_addr_is_low(end)) { >> unsigned long start_index = GET_HIGH_SLICE_INDEX(start); >> unsigned long align_end = ALIGN(end, (1UL << SLICE_HIGH_SHIFT)); >> unsigned long count = GET_HIGH_SLICE_INDEX(align_end) - start_index; >> @@ -304,7 +311,7 @@ static bool slice_scan_available(unsigned long addr, >> int end, unsigned long *boundary_addr) >> { >> unsigned long slice; >> - if (addr < SLICE_LOW_TOP) { >> + if (slice_addr_is_low(addr)) { >> slice = GET_LOW_SLICE_INDEX(addr); >> *boundary_addr = (slice + end) << SLICE_LOW_SHIFT; >> return !!(available->low_slices & (1u << slice)); >> @@ -707,7 +714,7 @@ unsigned int get_slice_psize(struct mm_struct *mm, unsigned long addr) >> >> VM_BUG_ON(radix_enabled()); >> >> - if (addr < SLICE_LOW_TOP) { >> + if (slice_addr_is_low(addr)) { >> psizes = mm->context.low_slices_psize; >> index = GET_LOW_SLICE_INDEX(addr); >> } else { >> -- >> 2.13.3 >>