[DTrace-devel] [PATCH v4 09/23] dtprobed: reparse the DOF stash when needed
Nick Alcock
nick.alcock at oracle.com
Wed Feb 21 20:48:03 UTC 2024
The DOF stash contains parsed DOF, i.e. instances of the dof_parsed_t
structure. When this structure changes, we need to arrange to reparse all
DOF we have previously parsed that we find in the stash at daemon startup.
Doing this requires adjusting process_dof so its prototype is suitable to
pass to reparse_dof as a reparse function. Since the reparse function may
be running long after the DOF itself is created, we can't go around grabbing
processes just to figure out their mapping (dev, ino)s: we can use the (dev,
ino) the DOF stash has already recorded. This means migrating the process
grab out of process_dof() into a new mapping_dev_inum(), called by
process_dof()'s caller, helper_ioctl().
(This process temporarily breaks probe creation, since currently it
requires a ps_prochandle that is no longer available from process_dof.
It will be repaired in the next commit.)
Signed-off-by: Nick Alcock <nick.alcock at oracle.com>
---
dtprobed/dtprobed.c | 118 ++++++++++++++++++++++++++++----------------
1 file changed, 76 insertions(+), 42 deletions(-)
diff --git a/dtprobed/dtprobed.c b/dtprobed/dtprobed.c
index 76c895ec58b76..b191f8e33b5ad 100644
--- a/dtprobed/dtprobed.c
+++ b/dtprobed/dtprobed.c
@@ -82,14 +82,15 @@ static void helper_ioctl(fuse_req_t req, int cmd, void *arg,
struct fuse_file_info *fi, unsigned int flags,
const void *in_buf, size_t in_bufsz, size_t out_bufsz);
-static int process_dof(fuse_req_t req, int out, int in, pid_t pid,
- dof_helper_t *dh, const void *in_buf, size_t in_bufsz,
- uintptr_t buf_addr);
-
static const struct cuse_lowlevel_ops dtprobed_clop = {
.ioctl = helper_ioctl,
};
+static int
+process_dof(pid_t pid, int out, int in, dev_t dev, ino_t inum,
+ dof_helper_t *dh, const void *in_buf, size_t in_bufsz,
+ int reparsing);
+
static void
log_msg(enum fuse_log_level level, const char *fmt, va_list ap)
{
@@ -446,6 +447,44 @@ create_probe(ps_prochandle *P, dof_parsed_t *provider, dof_parsed_t *probe,
mod, fun, prb));
}
+/*
+ * Get the (dev, inum) pair for the mapping the passed-in addr belongs to in the
+ * given pid. (If there are multiple, it doesn't matter which we choose as long
+ * as we are consistent.)
+ */
+static const int
+mapping_dev_inum(pid_t pid, uintptr_t addr, dev_t *dev, ino_t *inum)
+{
+ ps_prochandle *P;
+ const prmap_t *mapp;
+ int err = 0;
+
+ if ((P = Pgrab(pid, 2, 0, NULL, &err)) == NULL) {
+ fuse_log(FUSE_LOG_ERR, "%i: dtprobed: process grab failed: %s\n",
+ pid, strerror(err));
+ return -1;
+ }
+
+ mapp = Paddr_to_map(P, addr);
+
+ err = -1;
+ if (mapp == NULL) {
+ fuse_log(FUSE_LOG_ERR, "%i: dtprobed: cannot look up mapping (process dead?)\n",
+ pid);
+ goto out;
+ }
+
+ *dev = mapp->pr_dev;
+ *inum = mapp->pr_inum;
+
+ err = 0;
+out:
+ Prelease(P, PS_RELEASE_NORMAL);
+ Pfree(P);
+
+ return err;
+}
+
/*
* Core ioctl() helper. Repeatedly reinvoked after calls to
* fuse_reply_ioctl_retry, once per dereference.
@@ -460,6 +499,8 @@ helper_ioctl(fuse_req_t req, int cmd, void *arg,
dtprobed_userdata_t *userdata = get_userdata(pid);
const char *errmsg;
const void *buf;
+ dev_t dev = 0;
+ ino_t inum = 0;
int gen = 0;
/*
@@ -647,9 +688,12 @@ helper_ioctl(fuse_req_t req, int cmd, void *arg,
if (userdata->buf)
buf = userdata->buf;
- if (process_dof(req, parser_out_pipe, parser_in_pipe, pid,
- &userdata->dh, buf, userdata->dof_hdr.dofh_loadsz,
- userdata->dh.dofhp_dof) < 0)
+ if ((mapping_dev_inum(pid, userdata->dh.dofhp_dof, &dev, &inum)) < 0)
+ goto process_err;
+
+ if ((gen = process_dof(pid, parser_out_pipe, parser_in_pipe,
+ dev, inum, &userdata->dh, buf,
+ userdata->dof_hdr.dofh_loadsz, 0)) < 0)
goto process_err;
if (fuse_reply_ioctl(req, gen, NULL, 0) < 0)
@@ -695,37 +739,23 @@ helper_ioctl(fuse_req_t req, int cmd, void *arg,
/*
* Process some DOF, passing it to the parser and creating probes from it.
+ *
+ * If reparsing is set, we are re-parsing existing DOF and should only update
+ * the parsed DOF representation.
*/
static int
-process_dof(fuse_req_t req, int out, int in, pid_t pid,
- dof_helper_t *dh, const void *in_buf, size_t in_bufsz,
- uintptr_t buf_addr)
+process_dof(pid_t pid, int out, int in, dev_t dev, ino_t inum, dof_helper_t *dh,
+ const void *in_buf, size_t in_bufsz, int reparsing)
{
- int perr = 0;
- ps_prochandle *P;
dof_parsed_t *provider;
size_t i;
size_t tries = 0;
int gen = 0;
const char *errmsg;
dt_list_t accum = {0};
- const prmap_t *mapp;
+ ps_prochandle *P = NULL; /* temporary */
- if ((P = Pgrab(pid, 2, 0, NULL, &perr)) == NULL) {
- fuse_log(FUSE_LOG_ERR, "%i: dtprobed: process grab failed: %s\n",
- pid, strerror(perr));
- goto proc_err;
- }
-
- mapp = Paddr_to_map(P, buf_addr);
-
- if (mapp == NULL) {
- fuse_log(FUSE_LOG_ERR, "%i: dtprobed: cannot look up mapping (process dead?)\n",
- pid);
- goto release_err;
- }
-
- do {
+ do {
errmsg = "DOF parser write failed";
while ((errno = dof_parser_host_write(out, dh,
(dof_hdr_t *) in_buf)) == EAGAIN);
@@ -782,19 +812,18 @@ process_dof(fuse_req_t req, int out, int in, pid_t pid,
}
}
- Prelease(P, PS_RELEASE_NORMAL);
- Pfree(P);
- if ((gen = dof_stash_add(pid, mapp->pr_dev, mapp->pr_inum, dh, in_buf, in_bufsz)) < 0)
- goto fileio;
+ if (!reparsing)
+ if ((gen = dof_stash_add(pid, dev, inum, dh, in_buf, in_bufsz)) < 0)
+ goto fileio;
- if (dof_stash_write_parsed(pid, mapp->pr_dev, mapp->pr_inum, &accum) < 0) {
+ if (dof_stash_write_parsed(pid, dev, inum, &accum) < 0) {
dof_stash_free(&accum);
dof_stash_remove(pid, gen);
goto fileio;
}
dof_stash_free(&accum);
- return gen;
+ return gen;
oom:
fuse_log(FUSE_LOG_ERR, "%i: out of memory parsing DOF\n", pid);
@@ -802,17 +831,11 @@ oom:
err:
fuse_log(FUSE_LOG_ERR, "%i: dtprobed: parser error: %s\n", pid, errmsg);
- Prelease(P, PS_RELEASE_NORMAL);
- Pfree(P);
goto proc_err;
fileio:
- fuse_log(FUSE_LOG_ERR, "%i: dtprobed: I/O error stashing DOF: %s\n",
- pid, strerror(errno));
-
-release_err:
- Prelease(P, PS_RELEASE_NORMAL);
- Pfree(P);
+ fuse_log(FUSE_LOG_ERR, "%i: dtprobed: I/O error stashing DOF: %s\n",
+ pid, strerror(errno));
proc_err:
dof_stash_free(&accum);
@@ -1011,6 +1034,17 @@ main(int argc, char *argv[])
*/
dof_stash_prune_dead();
+ /*
+ * Make sure that old parsed DOF is deleted and reparsed: it might come
+ * from a prior daemon invocation, with an older daemon version with a
+ * different parsed DOF representation. If we can't do this, don't try
+ * restarting the daemon: it'll just fail again in the same way.
+ */
+ if (reparse_dof(parser_out_pipe, parser_in_pipe, process_dof, 0) < 0) {
+ teardown_device();
+ exit(1);
+ }
+
if (!foreground) {
close(sync_fd);
sync_fd = -1;
--
2.43.0.272.gce700b77fd
More information about the DTrace-devel
mailing list