From: Bodo Stroesser <bstroesser@ts.fujitsu.com> To: "Martin K. Petersen" <martin.petersen@oracle.com>, Mike Christie <michael.christie@oracle.com>, linux-scsi@vger.kernel.org, target-devel@vger.kernel.org Cc: JiangYu <lnsyyj@hotmail.com>, Daniel Meyerholt <dxm523@gmail.com>, Bodo Stroesser <bstroesser@ts.fujitsu.com> Subject: [PATCH 1/2 v2] scsi: target: tcmu: Optimize use of flush_dcache_page Date: Thu, 18 Jun 2020 13:16:31 +0000 [thread overview] Message-ID: <20200618131632.32748-2-bstroesser@ts.fujitsu.com> (raw) In-Reply-To: <20200618131632.32748-1-bstroesser@ts.fujitsu.com> (scatter|gather)_data_area() need to flush dcache after writing data to or before reading data from a page in uio data area. The two routines are able to handle data transfer to/from such a page in fragments and flush the cache after each fragment was copied by calling the wrapper tcmu_flush_dcache_range(). That means: 1) flush_dcache_page() can be called multiple times for the same page. 2) Calling flush_dcache_page() indirectly using the wrapper does not make sense, because each call of the wrapper is for one single page only and the calling routine already has the correct page pointer. Therefore I changed (scatter|gather)_data_area() such, that instead of calling tcmu_flush_dcache_range() before/after each memcpy, it now calls flush_dcache_page() before unmapping a page (when writing is complete for that page) or after mapping a page (when starting to read the page). After this change only calls to tcmu_flush_dcache_range() for addresses in vmalloc'ed command ring are left over. This is a good preparation for the second patch of the series. The patch was tested on ARM with kernel 4.19.118 and 5.7.2 Signed-off-by: Bodo Stroesser <bstroesser@ts.fujitsu.com> Tested-by: JiangYu <lnsyyj@hotmail.com> Tested-by: Daniel Meyerholt <dxm523@gmail.com> --- drivers/target/target_core_user.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c index 560bfec933bc..a65e9671ae7a 100644 --- a/drivers/target/target_core_user.c +++ b/drivers/target/target_core_user.c @@ -676,8 +676,10 @@ static void scatter_data_area(struct tcmu_dev *udev, from = kmap_atomic(sg_page(sg)) + sg->offset; while (sg_remaining > 0) { if (block_remaining = 0) { - if (to) + if (to) { + flush_dcache_page(page); kunmap_atomic(to); + } block_remaining = DATA_BLOCK_SIZE; dbi = tcmu_cmd_get_dbi(tcmu_cmd); @@ -722,7 +724,6 @@ static void scatter_data_area(struct tcmu_dev *udev, memcpy(to + offset, from + sg->length - sg_remaining, copy_bytes); - tcmu_flush_dcache_range(to, copy_bytes); } sg_remaining -= copy_bytes; @@ -731,8 +732,10 @@ static void scatter_data_area(struct tcmu_dev *udev, kunmap_atomic(from - sg->offset); } - if (to) + if (to) { + flush_dcache_page(page); kunmap_atomic(to); + } } static void gather_data_area(struct tcmu_dev *udev, struct tcmu_cmd *cmd, @@ -778,13 +781,13 @@ static void gather_data_area(struct tcmu_dev *udev, struct tcmu_cmd *cmd, dbi = tcmu_cmd_get_dbi(cmd); page = tcmu_get_block_page(udev, dbi); from = kmap_atomic(page); + flush_dcache_page(page); } copy_bytes = min_t(size_t, sg_remaining, block_remaining); if (read_len < copy_bytes) copy_bytes = read_len; offset = DATA_BLOCK_SIZE - block_remaining; - tcmu_flush_dcache_range(from, copy_bytes); memcpy(to + sg->length - sg_remaining, from + offset, copy_bytes); -- 2.12.3
WARNING: multiple messages have this Message-ID (diff)
From: Bodo Stroesser <bstroesser@ts.fujitsu.com> To: "Martin K. Petersen" <martin.petersen@oracle.com>, Mike Christie <michael.christie@oracle.com>, linux-scsi@vger.kernel.org, target-devel@vger.kernel.org Cc: JiangYu <lnsyyj@hotmail.com>, Daniel Meyerholt <dxm523@gmail.com>, Bodo Stroesser <bstroesser@ts.fujitsu.com> Subject: [PATCH 1/2 v2] scsi: target: tcmu: Optimize use of flush_dcache_page Date: Thu, 18 Jun 2020 15:16:31 +0200 [thread overview] Message-ID: <20200618131632.32748-2-bstroesser@ts.fujitsu.com> (raw) In-Reply-To: <20200618131632.32748-1-bstroesser@ts.fujitsu.com> (scatter|gather)_data_area() need to flush dcache after writing data to or before reading data from a page in uio data area. The two routines are able to handle data transfer to/from such a page in fragments and flush the cache after each fragment was copied by calling the wrapper tcmu_flush_dcache_range(). That means: 1) flush_dcache_page() can be called multiple times for the same page. 2) Calling flush_dcache_page() indirectly using the wrapper does not make sense, because each call of the wrapper is for one single page only and the calling routine already has the correct page pointer. Therefore I changed (scatter|gather)_data_area() such, that instead of calling tcmu_flush_dcache_range() before/after each memcpy, it now calls flush_dcache_page() before unmapping a page (when writing is complete for that page) or after mapping a page (when starting to read the page). After this change only calls to tcmu_flush_dcache_range() for addresses in vmalloc'ed command ring are left over. This is a good preparation for the second patch of the series. The patch was tested on ARM with kernel 4.19.118 and 5.7.2 Signed-off-by: Bodo Stroesser <bstroesser@ts.fujitsu.com> Tested-by: JiangYu <lnsyyj@hotmail.com> Tested-by: Daniel Meyerholt <dxm523@gmail.com> --- drivers/target/target_core_user.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c index 560bfec933bc..a65e9671ae7a 100644 --- a/drivers/target/target_core_user.c +++ b/drivers/target/target_core_user.c @@ -676,8 +676,10 @@ static void scatter_data_area(struct tcmu_dev *udev, from = kmap_atomic(sg_page(sg)) + sg->offset; while (sg_remaining > 0) { if (block_remaining == 0) { - if (to) + if (to) { + flush_dcache_page(page); kunmap_atomic(to); + } block_remaining = DATA_BLOCK_SIZE; dbi = tcmu_cmd_get_dbi(tcmu_cmd); @@ -722,7 +724,6 @@ static void scatter_data_area(struct tcmu_dev *udev, memcpy(to + offset, from + sg->length - sg_remaining, copy_bytes); - tcmu_flush_dcache_range(to, copy_bytes); } sg_remaining -= copy_bytes; @@ -731,8 +732,10 @@ static void scatter_data_area(struct tcmu_dev *udev, kunmap_atomic(from - sg->offset); } - if (to) + if (to) { + flush_dcache_page(page); kunmap_atomic(to); + } } static void gather_data_area(struct tcmu_dev *udev, struct tcmu_cmd *cmd, @@ -778,13 +781,13 @@ static void gather_data_area(struct tcmu_dev *udev, struct tcmu_cmd *cmd, dbi = tcmu_cmd_get_dbi(cmd); page = tcmu_get_block_page(udev, dbi); from = kmap_atomic(page); + flush_dcache_page(page); } copy_bytes = min_t(size_t, sg_remaining, block_remaining); if (read_len < copy_bytes) copy_bytes = read_len; offset = DATA_BLOCK_SIZE - block_remaining; - tcmu_flush_dcache_range(from, copy_bytes); memcpy(to + sg->length - sg_remaining, from + offset, copy_bytes); -- 2.12.3
next prev parent reply other threads:[~2020-06-18 13:16 UTC|newest] Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-06-18 13:16 [PATCH v2 0/2] scsi: target: tcmu: fix crashes on ARM Bodo Stroesser 2020-06-18 13:16 ` Bodo Stroesser 2020-06-18 13:16 ` Bodo Stroesser [this message] 2020-06-18 13:16 ` [PATCH 1/2 v2] scsi: target: tcmu: Optimize use of flush_dcache_page Bodo Stroesser 2020-06-18 13:16 ` [PATCH 2/2 v2] scsi: target: tcmu: Fix crash in tcmu_flush_dcache_range on ARM Bodo Stroesser 2020-06-18 13:16 ` Bodo Stroesser 2020-06-18 15:00 ` Mike Christie 2020-06-18 15:00 ` Mike Christie 2020-06-18 15:41 ` Bodo Stroesser 2020-06-18 15:41 ` Bodo Stroesser 2020-06-18 16:06 ` Mike Christie 2020-06-18 16:06 ` Mike Christie 2020-06-18 16:04 ` [PATCH v2 0/2] scsi: target: tcmu: fix crashes " Mike Christie 2020-06-18 16:04 ` Mike Christie 2020-06-20 3:26 ` Martin K. Petersen 2020-06-20 3:26 ` Martin K. Petersen 2020-08-28 8:43 ` Bodo Stroesser 2020-08-28 8:43 ` Bodo Stroesser
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