destroyed, the tokens are to be considered stale and subsequent
usage will result in errors.
+ - A valid adapter file descriptor (fd2 >= 0) is only returned on
+ the initial attach for a context. Subsequent attaches to an
+ existing context (DK_CXLFLASH_ATTACH_REUSE_CONTEXT flag present)
+ do not provide the adapter file descriptor as it was previously
+ made known to the application.
+
- When a context is no longer needed, the user shall detach from
- the context via the DK_CXLFLASH_DETACH ioctl.
+ the context via the DK_CXLFLASH_DETACH ioctl. When this ioctl
+ returns with a valid adapter file descriptor and the return flag
+ DK_CXLFLASH_APP_CLOSE_ADAP_FD is present, the application _must_
+ close the adapter file descriptor following a successful detach.
+
+ - When this ioctl returns with a valid fd2 and the return flag
+ DK_CXLFLASH_APP_CLOSE_ADAP_FD is present, the application _must_
+ close fd2 in the following circumstances:
+
+ + Following a successful detach of the last user of the context
+ + Following a successful recovery on the context's original fd2
+ + In the child process of a fork(), following a clone ioctl,
+ on the fd2 associated with the source context
- - A close on fd2 will invalidate the tokens. This operation is not
- required by the user.
+ - At any time, a close on fd2 will invalidate the tokens. Applications
+ should exercise caution to only close fd2 when appropriate (outlined
+ in the previous bullet) to avoid premature loss of I/O.
DK_CXLFLASH_USER_DIRECT
-----------------------
success, all "tokens" which had been provided to the user from the
DK_CXLFLASH_ATTACH onward are no longer valid.
+ When the DK_CXLFLASH_APP_CLOSE_ADAP_FD flag was returned on a successful
+ attach, the application _must_ close the fd2 associated with the context
+ following the detach of the final user of the context.
+
DK_CXLFLASH_VLUN_CLONE
----------------------
This ioctl is responsible for cloning a previously created
support maintaining user space access to storage after a process
forks. Upon success, the child process (which invoked the ioctl)
will have access to the same LUNs via the same resource handle(s)
- and fd2 as the parent, but under a different context.
+ as the parent, but under a different context.
Context sharing across processes is not supported with CXL and
therefore each fork must be met with establishing a new context
translation tables are copied from the parent context to the child's
and then synced with the AFU.
+ When the DK_CXLFLASH_APP_CLOSE_ADAP_FD flag was returned on a successful
+ attach, the application _must_ close the fd2 associated with the source
+ context (still resident/accessible in the parent process) following the
+ clone. This is to avoid a stale entry in the file descriptor table of the
+ child process.
+
DK_CXLFLASH_VERIFY
------------------
This ioctl is used to detect various changes such as the capacity of
at which time the context/resources they held will be freed as part of
the release fop.
+ When the DK_CXLFLASH_APP_CLOSE_ADAP_FD flag was returned on a successful
+ attach, the application _must_ unmap and close the fd2 associated with the
+ original context following this ioctl returning success and indicating that
+ the context was recovered (DK_CXLFLASH_RECOVER_AFU_CONTEXT_RESET).
+
DK_CXLFLASH_MANAGE_LUN
----------------------
This ioctl is used to switch a LUN from a mode where it is available
{
struct ctx_info *ctxi = container_of(kref, struct ctx_info, kref);
struct cxlflash_cfg *cfg = ctxi->cfg;
- int lfd;
u64 ctxid = DECODE_CTXID(ctxi->ctxid);
/* Remove context from table/error list */
mutex_unlock(&ctxi->mutex);
/* Context now completely uncoupled/unreachable */
- lfd = ctxi->lfd;
destroy_context(cfg, ctxi);
-
- /*
- * As a last step, clean up external resources when not
- * already on an external cleanup thread, i.e.: close(adap_fd).
- *
- * NOTE: this will free up the context from the CXL services,
- * allowing it to dole out the same context_id on a future
- * (or even currently in-flight) disk_attach operation.
- */
- if (lfd != -1)
- sys_close(lfd);
}
/**
*
* This routine is the release handler for the fops registered with
* the CXL services on an initial attach for a context. It is called
- * when a close is performed on the adapter file descriptor returned
- * to the user. Programmatically, the user is not required to perform
- * the close, as it is handled internally via the detach ioctl when
- * a context is being removed. Note that nothing prevents the user
- * from performing a close, but the user should be aware that doing
- * so is considered catastrophic and subsequent usage of the superpipe
- * API with previously saved off tokens will fail.
+ * when a close (explicity by the user or as part of a process tear
+ * down) is performed on the adapter file descriptor returned to the
+ * user. The user should be aware that explicitly performing a close
+ * considered catastrophic and subsequent usage of the superpipe API
+ * with previously saved off tokens will fail.
*
- * When initiated from an external close (either by the user or via
- * a process tear down), the routine derives the context reference
- * and calls detach for each LUN associated with the context. The
- * final detach operation will cause the context itself to be freed.
- * Note that the saved off lfd is reset prior to calling detach to
- * signify that the final detach should not perform a close.
- *
- * When initiated from a detach operation as part of the tear down
- * of a context, the context is first completely freed and then the
- * close is performed. This routine will fail to derive the context
- * reference (due to the context having already been freed) and then
- * call into the CXL release entry point.
- *
- * Thus, with exception to when the CXL process element (context id)
- * lookup fails (a case that should theoretically never occur), every
- * call into this routine results in a complete freeing of a context.
- *
- * As part of the detach, all per-context resources associated with the LUN
- * are cleaned up. When detaching the last LUN for a context, the context
- * itself is cleaned up and released.
+ * This routine derives the context reference and calls detach for
+ * each LUN associated with the context.The final detach operation
+ * causes the context itself to be freed. With exception to when the
+ * CXL process element (context id) lookup fails (a case that should
+ * theoretically never occur), every call into this routine results
+ * in a complete freeing of a context.
*
* Return: 0 on success
*/
goto out;
}
- dev_dbg(dev, "%s: close(%d) for context %d\n",
- __func__, ctxi->lfd, ctxid);
+ dev_dbg(dev, "%s: close for context %d\n", __func__, ctxid);
- /* Reset the file descriptor to indicate we're on a close() thread */
- ctxi->lfd = -1;
detach.context_id = ctxi->ctxid;
list_for_each_entry_safe(lun_access, t, &ctxi->luns, list)
_cxlflash_disk_detach(lun_access->sdev, ctxi, &detach);
__func__, rctxid);
kref_get(&ctxi->kref);
list_add(&lun_access->list, &ctxi->luns);
- fd = ctxi->lfd;
goto out_attach;
}
fd_install(fd, file);
out_attach:
- attach->hdr.return_flags = 0;
+ if (fd != -1)
+ attach->hdr.return_flags = DK_CXLFLASH_APP_CLOSE_ADAP_FD;
+ else
+ attach->hdr.return_flags = 0;
+
attach->context_id = ctxi->ctxid;
attach->block_size = gli->blk_len;
attach->mmio_size = sizeof(afu->afu_map->hosts[0].harea);
{
struct device *dev = &cfg->dev->dev;
int rc = 0;
- int old_fd, fd = -1;
+ int fd = -1;
int ctxid = -1;
struct file *file;
struct cxl_context *ctx;
* No error paths after this point. Once the fd is installed it's
* visible to user space and can't be undone safely on this thread.
*/
- old_fd = ctxi->lfd;
ctxi->ctxid = ENCODE_CTXID(ctxi, ctxid);
ctxi->lfd = fd;
ctxi->ctx = ctx;
cfg->ctx_tbl[ctxid] = ctxi;
mutex_unlock(&cfg->ctx_tbl_list_mutex);
fd_install(fd, file);
-
- /* Release the original adapter fd and associated CXL resources */
- sys_close(old_fd);
out:
dev_dbg(dev, "%s: returning ctxid=%d fd=%d rc=%d\n",
__func__, ctxid, fd, rc);
recover->context_id = ctxi->ctxid;
recover->adap_fd = ctxi->lfd;
recover->mmio_size = sizeof(afu->afu_map->hosts[0].harea);
- recover->hdr.return_flags |=
+ recover->hdr.return_flags = DK_CXLFLASH_APP_CLOSE_ADAP_FD |
DK_CXLFLASH_RECOVER_AFU_CONTEXT_RESET;
goto out;
}
ctxid_dst = DECODE_CTXID(clone->context_id_dst),
rctxid_src = clone->context_id_src,
rctxid_dst = clone->context_id_dst;
- int adap_fd_src = clone->adap_fd_src;
int i, j;
int rc = 0;
bool found;
LIST_HEAD(sidecar);
- pr_debug("%s: ctxid_src=%llu ctxid_dst=%llu adap_fd_src=%d\n",
- __func__, ctxid_src, ctxid_dst, adap_fd_src);
+ pr_debug("%s: ctxid_src=%llu ctxid_dst=%llu\n",
+ __func__, ctxid_src, ctxid_dst);
/* Do not clone yourself */
if (unlikely(rctxid_src == rctxid_dst)) {
goto out;
}
- if (unlikely(adap_fd_src != ctxi_src->lfd)) {
- pr_debug("%s: Invalid source adapter fd! (%d)\n",
- __func__, adap_fd_src);
- rc = -EINVAL;
- goto out;
- }
-
/* Verify there is no open resource handle in the destination context */
for (i = 0; i < MAX_RHT_PER_CONTEXT; i++)
if (ctxi_dst->rht_start[i].nmask != 0) {
out_success:
list_splice(&sidecar, &ctxi_dst->luns);
- sys_close(adap_fd_src);
/* fall through */
out:
* at this time, this provides future flexibility.
*/
#define DK_CXLFLASH_ALL_PORTS_ACTIVE 0x0000000000000001ULL
+#define DK_CXLFLASH_APP_CLOSE_ADAP_FD 0x0000000000000002ULL
/*
- * Notes:
- * -----
+ * General Notes:
+ * -------------
* The 'context_id' field of all ioctl structures contains the context
* identifier for a context in the lower 32-bits (upper 32-bits are not
* to be used when identifying a context to the AFU). That said, the value
* in its entirety (all 64-bits) is to be treated as an opaque cookie and
* should be presented as such when issuing ioctls.
+ */
+
+/*
+ * DK_CXLFLASH_ATTACH Notes:
+ * ------------------------
+ * Read/write access permissions are specified via the O_RDONLY, O_WRONLY,
+ * and O_RDWR flags defined in the fcntl.h header file.
*
- * For DK_CXLFLASH_ATTACH ioctl, user specifies read/write access
- * permissions via the O_RDONLY, O_WRONLY, and O_RDWR flags defined in
- * the fcntl.h header file.
+ * A valid adapter file descriptor (fd >= 0) is only returned on the initial
+ * attach (successful) of a context. When a context is shared(reused), the user
+ * is expected to already 'know' the adapter file descriptor associated with the
+ * context.
*/
#define DK_CXLFLASH_ATTACH_REUSE_CONTEXT 0x8000000000000000ULL
projects / GitHub / MotorolaMobilityLLC / kernel-slsi.git / commitdiff