From: Vishal Verma <vishal.l.verma@intel.com>
To: <linux-nvdimm@lists.01.org>
Cc: Ben Olson <ben.olson@intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>
Subject: [ndctl PATCH v2 02/10] libdaxctl: refactor memblock_is_online() checks
Date: Sat, 19 Oct 2019 21:23:24 -0600 [thread overview]
Message-ID: <20191020032332.16776-3-vishal.l.verma@intel.com> (raw)
In-Reply-To: <20191020032332.16776-1-vishal.l.verma@intel.com>
The {online,offline}_one_memblock() helpers both open-coded the check
for whether a block is online. There is already a function to perform
this check - memblock_is_online(). Consolidate the checking using this
helper everywhere it is applicable.
Cc: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
---
daxctl/lib/libdaxctl.c | 90 +++++++++++++++++-------------------------
1 file changed, 37 insertions(+), 53 deletions(-)
diff --git a/daxctl/lib/libdaxctl.c b/daxctl/lib/libdaxctl.c
index a828644..6243857 100644
--- a/daxctl/lib/libdaxctl.c
+++ b/daxctl/lib/libdaxctl.c
@@ -1047,12 +1047,11 @@ DAXCTL_EXPORT unsigned long daxctl_memory_get_block_size(struct daxctl_memory *m
return mem->block_size;
}
-static int online_one_memblock(struct daxctl_memory *mem, char *memblock)
+static int memblock_is_online(struct daxctl_memory *mem, char *memblock)
{
struct daxctl_dev *dev = daxctl_memory_get_dev(mem);
const char *devname = daxctl_dev_get_devname(dev);
struct daxctl_ctx *ctx = daxctl_dev_get_ctx(dev);
- const char *mode = "online_movable";
int len = mem->buf_len, rc;
char buf[SYSFS_ATTR_SIZE];
char *path = mem->mem_buf;
@@ -1073,41 +1072,20 @@ static int online_one_memblock(struct daxctl_memory *mem, char *memblock)
return rc;
}
- /*
- * if already online, possibly due to kernel config or a udev rule,
- * there is nothing to do and we can skip over the memblock
- */
if (strncmp(buf, "online", 6) == 0)
return 1;
- rc = sysfs_write_attr_quiet(ctx, path, mode);
- if (rc) {
- /*
- * While we performed an already-online check above, there
- * is still a TOCTOU hole where someone (such as a udev rule)
- * may have raced to online the memory. In such a case,
- * the sysfs store will fail, however we can check for this
- * by simply reading the state again. If it changed to the
- * desired state, then we don't have to error out.
- */
- if (sysfs_read_attr(ctx, path, buf) == 0) {
- if (strncmp(buf, "online", 6) == 0)
- return 1;
- }
- err(ctx, "%s: Failed to online %s: %s\n",
- devname, path, strerror(-rc));
- }
- return rc;
+ /* offline */
+ return 0;
}
-static int offline_one_memblock(struct daxctl_memory *mem, char *memblock)
+static int online_one_memblock(struct daxctl_memory *mem, char *memblock)
{
struct daxctl_dev *dev = daxctl_memory_get_dev(mem);
const char *devname = daxctl_dev_get_devname(dev);
struct daxctl_ctx *ctx = daxctl_dev_get_ctx(dev);
- const char *mode = "offline";
+ const char *mode = "online_movable";
int len = mem->buf_len, rc;
- char buf[SYSFS_ATTR_SIZE];
char *path = mem->mem_buf;
const char *node_path;
@@ -1119,37 +1097,39 @@ static int offline_one_memblock(struct daxctl_memory *mem, char *memblock)
if (rc < 0)
return -ENOMEM;
- rc = sysfs_read_attr(ctx, path, buf);
- if (rc) {
- err(ctx, "%s: Failed to read %s: %s\n",
- devname, path, strerror(-rc));
+ /*
+ * if already online, possibly due to kernel config or a udev rule,
+ * there is nothing to do and we can skip over the memblock
+ */
+ rc = memblock_is_online(mem, memblock);
+ if (rc)
return rc;
- }
-
- /* if already offline, there is nothing to do */
- if (strncmp(buf, "offline", 7) == 0)
- return 1;
rc = sysfs_write_attr_quiet(ctx, path, mode);
if (rc) {
- /* Close the TOCTOU hole like in online_one_memblock() above */
- if (sysfs_read_attr(ctx, path, buf) == 0) {
- if (strncmp(buf, "offline", 7) == 0)
- return 1;
- }
- err(ctx, "%s: Failed to offline %s: %s\n",
+ /*
+ * While we performed an already-online check above, there
+ * is still a TOCTOU hole where someone (such as a udev rule)
+ * may have raced to online the memory. In such a case,
+ * the sysfs store will fail, however we can check for this
+ * by simply reading the state again. If it changed to the
+ * desired state, then we don't have to error out.
+ */
+ if (memblock_is_online(mem, memblock))
+ return 1;
+ err(ctx, "%s: Failed to online %s: %s\n",
devname, path, strerror(-rc));
}
return rc;
}
-static int memblock_is_online(struct daxctl_memory *mem, char *memblock)
+static int offline_one_memblock(struct daxctl_memory *mem, char *memblock)
{
struct daxctl_dev *dev = daxctl_memory_get_dev(mem);
const char *devname = daxctl_dev_get_devname(dev);
struct daxctl_ctx *ctx = daxctl_dev_get_ctx(dev);
+ const char *mode = "offline";
int len = mem->buf_len, rc;
- char buf[SYSFS_ATTR_SIZE];
char *path = mem->mem_buf;
const char *node_path;
@@ -1161,18 +1141,22 @@ static int memblock_is_online(struct daxctl_memory *mem, char *memblock)
if (rc < 0)
return -ENOMEM;
- rc = sysfs_read_attr(ctx, path, buf);
- if (rc) {
- err(ctx, "%s: Failed to read %s: %s\n",
- devname, path, strerror(-rc));
+ /* if already offline, there is nothing to do */
+ rc = memblock_is_online(mem, memblock);
+ if (rc < 0)
return rc;
- }
-
- if (strncmp(buf, "online", 6) == 0)
+ if (!rc)
return 1;
- /* offline */
- return 0;
+ rc = sysfs_write_attr_quiet(ctx, path, mode);
+ if (rc) {
+ /* Close the TOCTOU hole like in online_one_memblock() above */
+ if (!memblock_is_online(mem, memblock))
+ return 1;
+ err(ctx, "%s: Failed to offline %s: %s\n",
+ devname, path, strerror(-rc));
+ }
+ return rc;
}
static bool memblock_in_dev(struct daxctl_memory *mem, const char *memblock)
--
2.20.1
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next prev parent reply other threads:[~2019-10-20 3:23 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-20 3:23 [ndctl PATCH v2 00/10] fixes and movability for system-ram mode Vishal Verma
2019-10-20 3:23 ` [ndctl PATCH v2 01/10] libdaxctl: refactor path construction in op_for_one_memblock() Vishal Verma
2019-10-20 3:23 ` Vishal Verma [this message]
2019-10-20 3:23 ` [ndctl PATCH v2 03/10] daxctl/device.c: fix json output omission for reconfigure-device Vishal Verma
2019-10-20 3:23 ` [ndctl PATCH v2 04/10] libdaxctl: add an API to determine if memory is movable Vishal Verma
2019-10-20 3:23 ` [ndctl PATCH v2 05/10] libdaxctl: allow memblock_in_dev() to return an error Vishal Verma
2019-10-20 3:23 ` [ndctl PATCH v2 06/10] daxctl: show a 'movable' attribute in device listings Vishal Verma
2019-10-20 3:23 ` [ndctl PATCH v2 07/10] daxctl: detect races when onlining memory blocks Vishal Verma
2019-10-20 3:23 ` [ndctl PATCH v2 08/10] Documentation: clarify memory movablity for reconfigure-device Vishal Verma
2019-10-20 3:23 ` [ndctl PATCH v2 09/10] libdaxctl: add an API to online memory in a non-movable state Vishal Verma
2019-10-20 3:23 ` [ndctl PATCH v2 10/10] daxctl: add --no-movable option for onlining memory Vishal Verma
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