+++ /dev/null
-From a4131a50d072b369bfed0b41e741c41fd8048641 Mon Sep 17 00:00:00 2001
-From: Naman Jain <namjain@linux.microsoft.com>
-Date: Fri, 11 Jul 2025 11:38:46 +0530
-Subject: tools/hv: fcopy: Fix irregularities with size of ring buffer
-
-From: Naman Jain <namjain@linux.microsoft.com>
-
-commit a4131a50d072b369bfed0b41e741c41fd8048641 upstream.
-
-Size of ring buffer, as defined in uio_hv_generic driver, is no longer
-fixed to 16 KB. This creates a problem in fcopy, since this size was
-hardcoded. With the change in place to make ring sysfs node actually
-reflect the size of underlying ring buffer, it is safe to get the size
-of ring sysfs file and use it for ring buffer size in fcopy daemon.
-Fix the issue of disparity in ring buffer size, by making it dynamic
-in fcopy uio daemon.
-
-Cc: stable@vger.kernel.org
-Fixes: 0315fef2aff9 ("uio_hv_generic: Align ring size to system page")
-Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
-Reviewed-by: Saurabh Sengar <ssengar@linux.microsoft.com>
-Reviewed-by: Long Li <longli@microsoft.com>
-Link: https://lore.kernel.org/r/20250711060846.9168-1-namjain@linux.microsoft.com
-Signed-off-by: Wei Liu <wei.liu@kernel.org>
-Message-ID: <20250711060846.9168-1-namjain@linux.microsoft.com>
-Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
----
- tools/hv/hv_fcopy_uio_daemon.c | 91 ++++++++++++++++++++++++++++++++++++-----
- 1 file changed, 81 insertions(+), 10 deletions(-)
-
---- a/tools/hv/hv_fcopy_uio_daemon.c
-+++ b/tools/hv/hv_fcopy_uio_daemon.c
-@@ -35,7 +35,10 @@
- #define WIN8_SRV_MINOR 1
- #define WIN8_SRV_VERSION (WIN8_SRV_MAJOR << 16 | WIN8_SRV_MINOR)
-
--#define FCOPY_UIO "/sys/bus/vmbus/devices/eb765408-105f-49b6-b4aa-c123b64d17d4/uio"
-+#define FCOPY_DEVICE_PATH(subdir) \
-+ "/sys/bus/vmbus/devices/eb765408-105f-49b6-b4aa-c123b64d17d4/" #subdir
-+#define FCOPY_UIO_PATH FCOPY_DEVICE_PATH(uio)
-+#define FCOPY_CHANNELS_PATH FCOPY_DEVICE_PATH(channels)
-
- #define FCOPY_VER_COUNT 1
- static const int fcopy_versions[] = {
-@@ -47,9 +50,62 @@ static const int fw_versions[] = {
- UTIL_FW_VERSION
- };
-
--#define HV_RING_SIZE 0x4000 /* 16KB ring buffer size */
-+static uint32_t get_ring_buffer_size(void)
-+{
-+ char ring_path[PATH_MAX];
-+ DIR *dir;
-+ struct dirent *entry;
-+ struct stat st;
-+ uint32_t ring_size = 0;
-+ int retry_count = 0;
-
--static unsigned char desc[HV_RING_SIZE];
-+ /* Find the channel directory */
-+ dir = opendir(FCOPY_CHANNELS_PATH);
-+ if (!dir) {
-+ usleep(100 * 1000); /* Avoid race with kernel, wait 100ms and retry once */
-+ dir = opendir(FCOPY_CHANNELS_PATH);
-+ if (!dir) {
-+ syslog(LOG_ERR, "Failed to open channels directory: %s", strerror(errno));
-+ return 0;
-+ }
-+ }
-+
-+retry_once:
-+ while ((entry = readdir(dir)) != NULL) {
-+ if (entry->d_type == DT_DIR && strcmp(entry->d_name, ".") != 0 &&
-+ strcmp(entry->d_name, "..") != 0) {
-+ snprintf(ring_path, sizeof(ring_path), "%s/%s/ring",
-+ FCOPY_CHANNELS_PATH, entry->d_name);
-+
-+ if (stat(ring_path, &st) == 0) {
-+ /*
-+ * stat returns size of Tx, Rx rings combined,
-+ * so take half of it for individual ring size.
-+ */
-+ ring_size = (uint32_t)st.st_size / 2;
-+ syslog(LOG_INFO, "Ring buffer size from %s: %u bytes",
-+ ring_path, ring_size);
-+ break;
-+ }
-+ }
-+ }
-+
-+ if (!ring_size && retry_count == 0) {
-+ retry_count = 1;
-+ rewinddir(dir);
-+ usleep(100 * 1000); /* Wait 100ms and retry once */
-+ goto retry_once;
-+ }
-+
-+ closedir(dir);
-+
-+ if (!ring_size)
-+ syslog(LOG_ERR, "Could not determine ring size");
-+
-+ return ring_size;
-+}
-+
-+static unsigned char *desc;
-
- static int target_fd;
- static char target_fname[PATH_MAX];
-@@ -406,7 +462,7 @@ int main(int argc, char *argv[])
- int daemonize = 1, long_index = 0, opt, ret = -EINVAL;
- struct vmbus_br txbr, rxbr;
- void *ring;
-- uint32_t len = HV_RING_SIZE;
-+ uint32_t ring_size, len;
- char uio_name[NAME_MAX] = {0};
- char uio_dev_path[PATH_MAX] = {0};
-
-@@ -437,7 +493,20 @@ int main(int argc, char *argv[])
- openlog("HV_UIO_FCOPY", 0, LOG_USER);
- syslog(LOG_INFO, "starting; pid is:%d", getpid());
-
-- fcopy_get_first_folder(FCOPY_UIO, uio_name);
-+ ring_size = get_ring_buffer_size();
-+ if (!ring_size) {
-+ ret = -ENODEV;
-+ goto exit;
-+ }
-+
-+ desc = malloc(ring_size * sizeof(unsigned char));
-+ if (!desc) {
-+ syslog(LOG_ERR, "malloc failed for desc buffer");
-+ ret = -ENOMEM;
-+ goto exit;
-+ }
-+
-+ fcopy_get_first_folder(FCOPY_UIO_PATH, uio_name);
- snprintf(uio_dev_path, sizeof(uio_dev_path), "/dev/%s", uio_name);
- fcopy_fd = open(uio_dev_path, O_RDWR);
-
-@@ -445,17 +514,17 @@ int main(int argc, char *argv[])
- syslog(LOG_ERR, "open %s failed; error: %d %s",
- uio_dev_path, errno, strerror(errno));
- ret = fcopy_fd;
-- goto exit;
-+ goto free_desc;
- }
-
-- ring = vmbus_uio_map(&fcopy_fd, HV_RING_SIZE);
-+ ring = vmbus_uio_map(&fcopy_fd, ring_size);
- if (!ring) {
- ret = errno;
- syslog(LOG_ERR, "mmap ringbuffer failed; error: %d %s", ret, strerror(ret));
- goto close;
- }
-- vmbus_br_setup(&txbr, ring, HV_RING_SIZE);
-- vmbus_br_setup(&rxbr, (char *)ring + HV_RING_SIZE, HV_RING_SIZE);
-+ vmbus_br_setup(&txbr, ring, ring_size);
-+ vmbus_br_setup(&rxbr, (char *)ring + ring_size, ring_size);
-
- rxbr.vbr->imask = 0;
-
-@@ -470,7 +539,7 @@ int main(int argc, char *argv[])
- continue;
- }
-
-- len = HV_RING_SIZE;
-+ len = ring_size;
- ret = rte_vmbus_chan_recv_raw(&rxbr, desc, &len);
- if (unlikely(ret <= 0)) {
- /* This indicates a failure to communicate (or worse) */
-@@ -490,6 +559,8 @@ int main(int argc, char *argv[])
- }
- close:
- close(fcopy_fd);
-+free_desc:
-+ free(desc);
- exit:
- return ret;
- }
projects / thirdparty / kernel / stable-queue.git / commitdiff
