[{"id":3678543,"web_url":"http://patchwork.ozlabs.org/comment/3678543/","msgid":"","date":"2026-04-17T07:58:21","subject":"Re: [PATCH] powerpc/perf/hv-gpci: bound sysfs formatting with\n sysfs_emit_at()","submitter":{"id":92089,"url":"http://patchwork.ozlabs.org/api/people/92089/","name":"Christophe Leroy (CS GROUP)","email":"chleroy@kernel.org"},"content":"Le 17/04/2026 à 09:48, Pengpeng Hou a écrit :\n> systeminfo_gpci_request() and\n> affinity_domain_via_partition_result_parse() hex-encode hypervisor data\n> into the single-page sysfs read buffer with sprintf(buf + *n, ...).\n> Both helpers only check PAGE_SIZE after the formatting loops have already\n> advanced past the end of the buffer.\n> \n> Switch these appends to sysfs_emit_at() and stop once the sysfs buffer is\n> full.\n\nYou are changing several time a single lines by multiples lines that \nlook pretty similar. Can you refactor in a helper function ?\n\n> \n> Fixes: 71f1c39647d8 (\"powerpc/hv_gpci: Add sysfs file inside hv_gpci device to show processor bus topology information\")\n> Fixes: a15e0d6a6929 (\"powerpc/hv_gpci: Add sysfs file inside hv_gpci device to show affinity domain via partition information\")\n> Cc: stable@vger.kernel.org\n> \n> Signed-off-by: Pengpeng Hou \n> ---\n> arch/powerpc/perf/hv-gpci.c | 56 +++++++++++++++++++++++++++++++------\n> 1 file changed, 47 insertions(+), 9 deletions(-)\n> \n> diff --git a/arch/powerpc/perf/hv-gpci.c b/arch/powerpc/perf/hv-gpci.c\n> index 5cac2cf3bd1e..325b80f01629 100644\n> --- a/arch/powerpc/perf/hv-gpci.c\n> +++ b/arch/powerpc/perf/hv-gpci.c\n> @@ -11,6 +11,7 @@\n> \n> #include \n> #include \n> +#include \n> #include \n> #include \n> #include \n> @@ -134,6 +135,7 @@ static unsigned long systeminfo_gpci_request(u32 req, u32 starting_index,\n> \t\t\tsize_t *n, struct hv_gpci_request_buffer *arg)\n> {\n> \tunsigned long ret;\n> +\tint len;\n> \tsize_t i, j;\n> \n> \targ->params.counter_request = cpu_to_be32(req);\n> @@ -176,9 +178,17 @@ static unsigned long systeminfo_gpci_request(u32 req, u32 starting_index,\n> \tfor (i = 0; i < be16_to_cpu(arg->params.returned_values); i++) {\n> \t\tj = i * be16_to_cpu(arg->params.cv_element_size);\n> \n> -\t\tfor (; j < (i + 1) * be16_to_cpu(arg->params.cv_element_size); j++)\n> -\t\t\t*n += sprintf(buf + *n, \"%02x\", (u8)arg->bytes[j]);\n> -\t\t*n += sprintf(buf + *n, \"\\n\");\n> +\t\tfor (; j < (i + 1) * be16_to_cpu(arg->params.cv_element_size);\n> +\t\t j++) {\n> +\t\t\tlen = sysfs_emit_at(buf, *n, \"%02x\", (u8)arg->bytes[j]);\n> +\t\t\tif (!len)\n> +\t\t\t\treturn -EFBIG;\n> +\t\t\t*n += len;\n> +\t\t}\n> +\t\tlen = sysfs_emit_at(buf, *n, \"\\n\");\n> +\t\tif (!len)\n> +\t\t\treturn -EFBIG;\n> +\t\t*n += len;\n> \t}\n> \n> \tif (*n >= PAGE_SIZE) {\n> @@ -465,6 +475,7 @@ static void affinity_domain_via_partition_result_parse(int returned_values,\n> \t\t\tint element_size, char *buf, size_t *last_element,\n> \t\t\tsize_t *n, struct hv_gpci_request_buffer *arg)\n> {\n> +\tint len;\n> \tsize_t i = 0, j = 0;\n> \tsize_t k, l, m;\n> \tuint16_t total_affinity_domain_ele, size_of_each_affinity_domain_ele;\n> @@ -483,22 +494,49 @@ static void affinity_domain_via_partition_result_parse(int returned_values,\n> \t */\n> \twhile (i < returned_values) {\n> \t\tk = j;\n> -\t\tfor (; k < j + element_size; k++)\n> -\t\t\t*n += sprintf(buf + *n, \"%02x\", (u8)arg->bytes[k]);\n> -\t\t*n += sprintf(buf + *n, \"\\n\");\n> +\t\tfor (; k < j + element_size; k++) {\n> +\t\t\tlen = sysfs_emit_at(buf, *n, \"%02x\", (u8)arg->bytes[k]);\n> +\t\t\tif (!len) {\n> +\t\t\t\t*n = PAGE_SIZE;\n> +\t\t\t\treturn;\n> +\t\t\t}\n> +\t\t\t*n += len;\n> +\t\t}\n> +\t\tlen = sysfs_emit_at(buf, *n, \"\\n\");\n> +\t\tif (!len) {\n> +\t\t\t*n = PAGE_SIZE;\n> +\t\t\treturn;\n> +\t\t}\n> +\t\t*n += len;\n> \n> \t\ttotal_affinity_domain_ele = (u8)arg->bytes[k - 2] << 8 | (u8)arg->bytes[k - 3];\n> \t\tsize_of_each_affinity_domain_ele = (u8)arg->bytes[k] << 8 | (u8)arg->bytes[k - 1];\n> \n> \t\tfor (l = 0; l < total_affinity_domain_ele; l++) {\n> \t\t\tfor (m = 0; m < size_of_each_affinity_domain_ele; m++) {\n> -\t\t\t\t*n += sprintf(buf + *n, \"%02x\", (u8)arg->bytes[k]);\n> +\t\t\t\tlen = sysfs_emit_at(buf, *n, \"%02x\",\n> +\t\t\t\t\t\t (u8)arg->bytes[k]);\n> +\t\t\t\tif (!len) {\n> +\t\t\t\t\t*n = PAGE_SIZE;\n> +\t\t\t\t\treturn;\n> +\t\t\t\t}\n> +\t\t\t\t*n += len;\n> \t\t\t\tk++;\n> \t\t\t}\n> -\t\t\t*n += sprintf(buf + *n, \"\\n\");\n> +\t\t\tlen = sysfs_emit_at(buf, *n, \"\\n\");\n> +\t\t\tif (!len) {\n> +\t\t\t\t*n = PAGE_SIZE;\n> +\t\t\t\treturn;\n> +\t\t\t}\n> +\t\t\t*n += len;\n> \t\t}\n> \n> -\t\t*n += sprintf(buf + *n, \"\\n\");\n> +\t\tlen = sysfs_emit_at(buf, *n, \"\\n\");\n> +\t\tif (!len) {\n> +\t\t\t*n = PAGE_SIZE;\n> +\t\t\treturn;\n> +\t\t}\n> +\t\t*n += len;\n> \t\ti++;\n> \t\tj = k;\n> \t}","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linuxppc-dev@lists.ozlabs.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256\n header.s=k20201202 header.b=IBOpVpJg;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org\n (client-ip=2404:9400:21b9:f100::1; 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