Re: [PATCH 6/9] pstore/zone: split struct pstore_zone_info
From: Kees Cook
Date: Tue Dec 01 2020 - 14:43:37 EST
On Fri, Oct 16, 2020 at 03:20:44PM +0200, Christoph Hellwig wrote:
> Split out a new pstore_zone_ops structure for static function pointers
> plus the name. Also remove the unused owner field entirely.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
On the face of it, this seems fine, but I don't think it's really useful
to split the structure up. There's a lot of churn here.
-Kees
> ---
> drivers/mtd/mtdpstore.c | 13 +++++++----
> fs/pstore/blk.c | 23 ++++++++++---------
> fs/pstore/zone.c | 46 +++++++++++++++++++------------------
> include/linux/pstore_blk.h | 23 ++-----------------
> include/linux/pstore_zone.h | 41 ++++++++++++++++++---------------
> 5 files changed, 69 insertions(+), 77 deletions(-)
>
> diff --git a/drivers/mtd/mtdpstore.c b/drivers/mtd/mtdpstore.c
> index a3ae8778f6a9b9..232ba5c39c2a55 100644
> --- a/drivers/mtd/mtdpstore.c
> +++ b/drivers/mtd/mtdpstore.c
> @@ -378,6 +378,14 @@ static ssize_t mtdpstore_panic_write(const char *buf, size_t size, loff_t off)
> return retlen;
> }
>
> +static const struct pstore_zone_ops mtdpstore_ops = {
> + .name = KBUILD_MODNAME,
> + .read = mtdpstore_read,
> + .write = mtdpstore_write,
> + .erase = mtdpstore_erase,
> + .panic_write = mtdpstore_panic_write,
> +};
> +
> static void mtdpstore_notify_add(struct mtd_info *mtd)
> {
> int ret;
> @@ -426,10 +434,7 @@ static void mtdpstore_notify_add(struct mtd_info *mtd)
> cxt->dev.total_size = mtd->size;
> /* just support dmesg right now */
> cxt->dev.flags = PSTORE_FLAGS_DMESG;
> - cxt->dev.read = mtdpstore_read;
> - cxt->dev.write = mtdpstore_write;
> - cxt->dev.erase = mtdpstore_erase;
> - cxt->dev.panic_write = mtdpstore_panic_write;
> + cxt->dev.ops = &mtdpstore_ops;
>
> ret = register_pstore_device(&cxt->dev);
> if (ret) {
> diff --git a/fs/pstore/blk.c b/fs/pstore/blk.c
> index a8aa56cba96d59..f7c7f325e42c71 100644
> --- a/fs/pstore/blk.c
> +++ b/fs/pstore/blk.c
> @@ -108,7 +108,8 @@ static int __register_pstore_device(struct pstore_device_info *dev)
>
> lockdep_assert_held(&pstore_blk_lock);
>
> - if (!dev || !dev->total_size || !dev->read || !dev->write)
> + if (!dev || !dev->total_size || !dev->ops ||
> + !dev->ops->read || !dev->ops->write)
> return -EINVAL;
>
> /* someone already registered before */
> @@ -141,12 +142,7 @@ static int __register_pstore_device(struct pstore_device_info *dev)
>
> pstore_zone_info->total_size = dev->total_size;
> pstore_zone_info->max_reason = max_reason;
> - pstore_zone_info->read = dev->read;
> - pstore_zone_info->write = dev->write;
> - pstore_zone_info->erase = dev->erase;
> - pstore_zone_info->panic_write = dev->panic_write;
> - pstore_zone_info->name = KBUILD_MODNAME;
> - pstore_zone_info->owner = THIS_MODULE;
> + pstore_zone_info->ops = dev->ops;
>
> ret = register_pstore_zone(pstore_zone_info);
> if (ret) {
> @@ -179,7 +175,7 @@ EXPORT_SYMBOL_GPL(register_pstore_device);
> static void __unregister_pstore_device(struct pstore_device_info *dev)
> {
> lockdep_assert_held(&pstore_blk_lock);
> - if (pstore_zone_info && pstore_zone_info->read == dev->read) {
> + if (pstore_zone_info && pstore_zone_info->ops == dev->ops) {
> unregister_pstore_zone(pstore_zone_info);
> kfree(pstore_zone_info);
> pstore_zone_info = NULL;
> @@ -265,6 +261,12 @@ static ssize_t psblk_generic_blk_write(const char *buf, size_t bytes,
> return ret;
> }
>
> +static const struct pstore_zone_ops pstore_blk_zone_ops = {
> + .name = KBUILD_MODNAME,
> + .read = psblk_generic_blk_read,
> + .write = psblk_generic_blk_write,
> +};
> +
> static int __init pstore_blk_init(void)
> {
> char bdev_name[BDEVNAME_SIZE];
> @@ -305,9 +307,8 @@ static int __init pstore_blk_init(void)
> psblk_bdev = bdev;
>
> memset(&dev, 0, sizeof(dev));
> + dev.ops = &pstore_blk_zone_ops;
> dev.total_size = nr_sects << SECTOR_SHIFT;
> - dev.read = psblk_generic_blk_read;
> - dev.write = psblk_generic_blk_write;
>
> ret = register_pstore_device(&dev);
> if (ret)
> @@ -326,7 +327,7 @@ late_initcall(pstore_blk_init);
>
> static void __exit pstore_blk_exit(void)
> {
> - struct pstore_device_info dev = { .read = psblk_generic_blk_read };
> + struct pstore_device_info dev = { .ops = &pstore_blk_zone_ops };
>
> if (!psblk_bdev)
> return;
> diff --git a/fs/pstore/zone.c b/fs/pstore/zone.c
> index 5266ccbec007f3..111d26bb2a8f56 100644
> --- a/fs/pstore/zone.c
> +++ b/fs/pstore/zone.c
> @@ -218,7 +218,7 @@ static int psz_zone_write(struct pstore_zone *zone,
> if (!is_on_panic() && !atomic_read(&pstore_zone_cxt.recovered))
> goto dirty;
>
> - writeop = is_on_panic() ? info->panic_write : info->write;
> + writeop = is_on_panic() ? info->ops->panic_write : info->ops->write;
> if (!writeop)
> goto dirty;
>
> @@ -337,7 +337,7 @@ static int psz_kmsg_recover_data(struct psz_context *cxt)
> unsigned long i;
> ssize_t rcnt;
>
> - if (!info->read)
> + if (!info->ops->read)
> return -EINVAL;
>
> for (i = 0; i < cxt->kmsg_max_cnt; i++) {
> @@ -360,8 +360,8 @@ static int psz_kmsg_recover_data(struct psz_context *cxt)
> if (!zone->should_recover)
> continue;
> buf = zone->buffer;
> - rcnt = info->read((char *)buf, zone->buffer_size + sizeof(*buf),
> - zone->off);
> + rcnt = info->ops->read((char *)buf, zone->buffer_size +
> + sizeof(*buf), zone->off);
> if (rcnt != zone->buffer_size + sizeof(*buf))
> return (int)rcnt < 0 ? (int)rcnt : -EIO;
> }
> @@ -383,7 +383,7 @@ static int psz_kmsg_recover_meta(struct psz_context *cxt)
> */
> char buffer_header[sizeof(*buf) + sizeof(*hdr)] = {0};
>
> - if (!info->read)
> + if (!info->ops->read)
> return -EINVAL;
>
> len = sizeof(*buf) + sizeof(*hdr);
> @@ -393,13 +393,14 @@ static int psz_kmsg_recover_meta(struct psz_context *cxt)
> if (unlikely(!zone))
> return -EINVAL;
>
> - rcnt = info->read((char *)buf, len, zone->off);
> + rcnt = info->ops->read((char *)buf, len, zone->off);
> if (rcnt == -ENOMSG) {
> pr_debug("%s with id %lu may be broken, skip\n",
> zone->name, i);
> continue;
> } else if (rcnt != len) {
> - pr_err("read %s with id %lu failed\n", zone->name, i);
> + pr_err("read %s with id %lu failed\n", zone->name,
> + i);
> return (int)rcnt < 0 ? (int)rcnt : -EIO;
> }
>
> @@ -495,11 +496,11 @@ static int psz_recover_zone(struct psz_context *cxt, struct pstore_zone *zone)
> return 0;
> }
>
> - if (unlikely(!info->read))
> + if (unlikely(!info->ops->read))
> return -EINVAL;
>
> len = sizeof(struct psz_buffer);
> - rcnt = info->read((char *)&tmpbuf, len, zone->off);
> + rcnt = info->ops->read((char *)&tmpbuf, len, zone->off);
> if (rcnt != len) {
> pr_debug("read zone %s failed\n", zone->name);
> return (int)rcnt < 0 ? (int)rcnt : -EIO;
> @@ -541,7 +542,7 @@ static int psz_recover_zone(struct psz_context *cxt, struct pstore_zone *zone)
> off = zone->off + sizeof(*oldbuf);
>
> /* get part of data */
> - rcnt = info->read(buf, len - start, off + start);
> + rcnt = info->ops->read(buf, len - start, off + start);
> if (rcnt != len - start) {
> pr_err("read zone %s failed\n", zone->name);
> ret = (int)rcnt < 0 ? (int)rcnt : -EIO;
> @@ -549,7 +550,7 @@ static int psz_recover_zone(struct psz_context *cxt, struct pstore_zone *zone)
> }
>
> /* get the rest of data */
> - rcnt = info->read(buf + len - start, start, off);
> + rcnt = info->ops->read(buf + len - start, start, off);
> if (rcnt != start) {
> pr_err("read zone %s failed\n", zone->name);
> ret = (int)rcnt < 0 ? (int)rcnt : -EIO;
> @@ -671,8 +672,8 @@ static inline int psz_kmsg_erase(struct psz_context *cxt,
>
> size = buffer_datalen(zone) + sizeof(*zone->buffer);
> atomic_set(&zone->buffer->datalen, 0);
> - if (cxt->pstore_zone_info->erase)
> - return cxt->pstore_zone_info->erase(size, zone->off);
> + if (cxt->pstore_zone_info->ops->erase)
> + return cxt->pstore_zone_info->ops->erase(size, zone->off);
> else
> return psz_zone_write(zone, FLUSH_META, NULL, 0, 0);
> }
> @@ -1185,8 +1186,9 @@ static struct pstore_zone *psz_init_zone(enum pstore_type_id type,
>
> *off += size;
>
> - pr_debug("pszone %s: off 0x%llx, %zu header, %zu data\n", zone->name,
> - zone->off, sizeof(*zone->buffer), zone->buffer_size);
> + pr_debug("pszone %s: off 0x%llx, %zu header, %zu data\n",
> + zone->name, zone->off, sizeof(*zone->buffer),
> + zone->buffer_size);
> return zone;
> }
>
> @@ -1310,7 +1312,7 @@ int register_pstore_zone(struct pstore_zone_info *info)
> return -EINVAL;
> }
>
> - if (!info->name || !info->name[0])
> + if (!info->ops->name || !info->ops->name[0])
> return -EINVAL;
>
> #define check_size(name, size) { \
> @@ -1338,7 +1340,7 @@ int register_pstore_zone(struct pstore_zone_info *info)
> * if no @read, pstore may mount failed.
> * if no @write, pstore do not support to remove record file.
> */
> - if (!info->read || !info->write) {
> + if (!info->ops || !info->ops->read || !info->ops->write) {
> pr_err("no valid general read/write interface\n");
> return -EINVAL;
> }
> @@ -1346,13 +1348,13 @@ int register_pstore_zone(struct pstore_zone_info *info)
> mutex_lock(&cxt->pstore_zone_info_lock);
> if (cxt->pstore_zone_info) {
> pr_warn("'%s' already loaded: ignoring '%s'\n",
> - cxt->pstore_zone_info->name, info->name);
> + cxt->pstore_zone_info->ops->name, info->ops->name);
> mutex_unlock(&cxt->pstore_zone_info_lock);
> return -EBUSY;
> }
> cxt->pstore_zone_info = info;
>
> - pr_debug("register %s with properties:\n", info->name);
> + pr_debug("register %s with properties:\n", info->ops->name);
> pr_debug("\ttotal size : %ld Bytes\n", info->total_size);
> pr_debug("\tkmsg size : %ld Bytes\n", info->kmsg_size);
> pr_debug("\tpmsg size : %ld Bytes\n", info->pmsg_size);
> @@ -1376,14 +1378,14 @@ int register_pstore_zone(struct pstore_zone_info *info)
> }
> cxt->pstore.data = cxt;
>
> - pr_info("registered %s as backend for", info->name);
> + pr_info("registered %s as backend for", info->ops->name);
> cxt->pstore.max_reason = info->max_reason;
> - cxt->pstore.name = info->name;
> + cxt->pstore.name = info->ops->name;
> if (info->kmsg_size) {
> cxt->pstore.flags |= PSTORE_FLAGS_DMESG;
> pr_cont(" kmsg(%s",
> kmsg_dump_reason_str(cxt->pstore.max_reason));
> - if (cxt->pstore_zone_info->panic_write)
> + if (cxt->pstore_zone_info->ops->panic_write)
> pr_cont(",panic_write");
> pr_cont(")");
> }
> diff --git a/include/linux/pstore_blk.h b/include/linux/pstore_blk.h
> index 99564f93d77488..095a44ce5e122c 100644
> --- a/include/linux/pstore_blk.h
> +++ b/include/linux/pstore_blk.h
> @@ -15,31 +15,12 @@
> * @flags: Refer to macro starting with PSTORE_FLAGS defined in
> * linux/pstore.h. It means what front-ends this device support.
> * Zero means all backends for compatible.
> - * @read: The general read operation. Both of the function parameters
> - * @size and @offset are relative value to bock device (not the
> - * whole disk).
> - * On success, the number of bytes should be returned, others
> - * means error.
> - * @write: The same as @read, but the following error number:
> - * -EBUSY means try to write again later.
> - * -ENOMSG means to try next zone.
> - * @erase: The general erase operation for device with special removing
> - * job. Both of the function parameters @size and @offset are
> - * relative value to storage.
> - * Return 0 on success and others on failure.
> - * @panic_write:The write operation only used for panic case. It's optional
> - * if you do not care panic log. The parameters are relative
> - * value to storage.
> - * On success, the number of bytes should be returned, others
> - * excluding -ENOMSG mean error. -ENOMSG means to try next zone.
> + * @ops: operations to access the device.
> */
> struct pstore_device_info {
> unsigned long total_size;
> unsigned int flags;
> - pstore_zone_read_op read;
> - pstore_zone_write_op write;
> - pstore_zone_erase_op erase;
> - pstore_zone_write_op panic_write;
> + const struct pstore_zone_ops *ops;
> };
>
> int register_pstore_device(struct pstore_device_info *dev);
> diff --git a/include/linux/pstore_zone.h b/include/linux/pstore_zone.h
> index 1e35eaa33e5e0d..7bff124c96d8b1 100644
> --- a/include/linux/pstore_zone.h
> +++ b/include/linux/pstore_zone.h
> @@ -5,22 +5,10 @@
>
> #include <linux/types.h>
>
> -typedef ssize_t (*pstore_zone_read_op)(char *, size_t, loff_t);
> -typedef ssize_t (*pstore_zone_write_op)(const char *, size_t, loff_t);
> -typedef ssize_t (*pstore_zone_erase_op)(size_t, loff_t);
> /**
> - * struct pstore_zone_info - pstore/zone back-end driver structure
> + * struct pstore_zone_ops - pstore/zone ops structure
> *
> - * @owner: Module which is responsible for this back-end driver.
> * @name: Name of the back-end driver.
> - * @total_size: The total size in bytes pstore/zone can use. It must be greater
> - * than 4096 and be multiple of 4096.
> - * @kmsg_size: The size of oops/panic zone. Zero means disabled, otherwise,
> - * it must be multiple of SECTOR_SIZE(512 Bytes).
> - * @max_reason: Maximum kmsg dump reason to store.
> - * @pmsg_size: The size of pmsg zone which is the same as @kmsg_size.
> - * @console_size:The size of console zone which is the same as @kmsg_size.
> - * @ftrace_size:The size of ftrace zone which is the same as @kmsg_size.
> * @read: The general read operation. Both of the function parameters
> * @size and @offset are relative value to storage.
> * On success, the number of bytes should be returned, others
> @@ -38,20 +26,35 @@ typedef ssize_t (*pstore_zone_erase_op)(size_t, loff_t);
> * On success, the number of bytes should be returned, others
> * excluding -ENOMSG mean error. -ENOMSG means to try next zone.
> */
> -struct pstore_zone_info {
> - struct module *owner;
> +struct pstore_zone_ops {
> const char *name;
> + ssize_t (*read)(char *buf, size_t count, loff_t pos);
> + ssize_t (*write)(const char *buf, size_t bytes, loff_t pos);
> + ssize_t (*erase)(size_t byes, loff_t pos);
> + ssize_t (*panic_write)(const char *buf, size_t bytes, loff_t pos);
> +};
>
> +/**
> + * struct pstore_zone_info - pstore/zone back-end driver structure
> + *
> + * @ops: Operations to access the zone.
> + * @total_size: The total size in bytes pstore/zone can use. It must be greater
> + * than 4096 and be multiple of 4096.
> + * @kmsg_size: The size of oops/panic zone. Zero means disabled, otherwise,
> + * it must be multiple of SECTOR_SIZE(512 Bytes).
> + * @max_reason: Maximum kmsg dump reason to store.
> + * @pmsg_size: The size of pmsg zone which is the same as @kmsg_size.
> + * @console_size:The size of console zone which is the same as @kmsg_size.
> + * @ftrace_size:The size of ftrace zone which is the same as @kmsg_size.
> + */
> +struct pstore_zone_info {
> + const struct pstore_zone_ops *ops;
> unsigned long total_size;
> unsigned long kmsg_size;
> int max_reason;
> unsigned long pmsg_size;
> unsigned long console_size;
> unsigned long ftrace_size;
> - pstore_zone_read_op read;
> - pstore_zone_write_op write;
> - pstore_zone_erase_op erase;
> - pstore_zone_write_op panic_write;
> };
>
> extern int register_pstore_zone(struct pstore_zone_info *info);
> --
> 2.28.0
>
--
Kees Cook