From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx>
Add tracefs_cpu_alloc_fd() to attach a tracefs_cpu descriptor to an
already opened file descriptor, and tracefs_cpu_free_fd() to clean up the
descriptor that tracefs_cpu_alloc_fd() created.
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
---
include/tracefs.h | 2 +
src/tracefs-record.c | 118 +++++++++++++++++++++++++++++--------------
2 files changed, 83 insertions(+), 37 deletions(-)
diff --git a/include/tracefs.h b/include/tracefs.h
index f500cb47c372..fd4f0668e7cc 100644
--- a/include/tracefs.h
+++ b/include/tracefs.h
@@ -597,9 +597,11 @@ tracefs_synth_get_event(struct tep_handle *tep, struct tracefs_synth *synth);
struct tracefs_cpu;
+struct tracefs_cpu *tracefs_cpu_alloc_fd(int fd, int subbuf_size, bool nonblock);
struct tracefs_cpu *tracefs_cpu_open(struct tracefs_instance *instance,
int cpu, bool nonblock);
void tracefs_cpu_close(struct tracefs_cpu *tcpu);
+void tracefs_cpu_free_fd(struct tracefs_cpu *tcpu);
int tracefs_cpu_read_size(struct tracefs_cpu *tcpu);
int tracefs_cpu_read(struct tracefs_cpu *tcpu, void *buffer, bool nonblock);
int tracefs_cpu_buffered_read(struct tracefs_cpu *tcpu, void *buffer, bool nonblock);
diff --git a/src/tracefs-record.c b/src/tracefs-record.c
index a59614de05ab..4ef3a259a203 100644
--- a/src/tracefs-record.c
+++ b/src/tracefs-record.c
@@ -24,7 +24,6 @@ enum {
};
struct tracefs_cpu {
- int cpu;
int fd;
int flags;
int nfds;
@@ -37,25 +36,21 @@ struct tracefs_cpu {
};
/**
- * tracefs_cpu_open - open an instance raw trace file
- * @instance: the instance (NULL for toplevel) of the cpu raw file to open
- * @cpu: The CPU that the raw trace file is associated with
+ * tracefs_cpu_alloc_fd - create a tracefs_cpu instance for an existing fd
+ * @fd: The file descriptor to attach the tracefs_cpu to
+ * @subbuf_size: The expected size to read the subbuffer with
* @nonblock: If true, the file will be opened in O_NONBLOCK mode
*
* Return a descriptor that can read the tracefs trace_pipe_raw file
- * for a give @cpu in a given @instance.
+ * that is associated with the given @fd and must be read in @subbuf_size.
*
* Returns NULL on error.
*/
struct tracefs_cpu *
-tracefs_cpu_open(struct tracefs_instance *instance, int cpu, bool nonblock)
+tracefs_cpu_alloc_fd(int fd, int subbuf_size, bool nonblock)
{
struct tracefs_cpu *tcpu;
- struct tep_handle *tep;
int mode = O_RDONLY;
- char path[128];
- char *buf;
- int len;
int ret;
tcpu = calloc(1, sizeof(*tcpu));
@@ -70,14 +65,62 @@ tracefs_cpu_open(struct tracefs_instance *instance, int cpu, bool nonblock)
tcpu->splice_pipe[0] = -1;
tcpu->splice_pipe[1] = -1;
+ tcpu->fd = fd;
+
+ tcpu->subbuf_size = subbuf_size;
+
+ if (tcpu->flags & TC_NONBLOCK) {
+ tcpu->ctrl_pipe[0] = -1;
+ tcpu->ctrl_pipe[1] = -1;
+ } else {
+ /* ctrl_pipe is used to break out of blocked reads */
+ ret = pipe(tcpu->ctrl_pipe);
+ if (ret < 0)
+ goto fail;
+ if (tcpu->ctrl_pipe[0] > tcpu->fd)
+ tcpu->nfds = tcpu->ctrl_pipe[0] + 1;
+ else
+ tcpu->nfds = tcpu->fd + 1;
+ }
+
+ return tcpu;
+ fail:
+ free(tcpu);
+ return NULL;
+}
+
+/**
+ * tracefs_cpu_open - open an instance raw trace file
+ * @instance: the instance (NULL for toplevel) of the cpu raw file to open
+ * @cpu: The CPU that the raw trace file is associated with
+ * @nonblock: If true, the file will be opened in O_NONBLOCK mode
+ *
+ * Return a descriptor that can read the tracefs trace_pipe_raw file
+ * for a give @cpu in a given @instance.
+ *
+ * Returns NULL on error.
+ */
+struct tracefs_cpu *
+tracefs_cpu_open(struct tracefs_instance *instance, int cpu, bool nonblock)
+{
+ struct tracefs_cpu *tcpu;
+ struct tep_handle *tep;
+ char path[128];
+ char *buf;
+ int mode = O_RDONLY;
+ int subbuf_size;
+ int len;
+ int ret;
+ int fd;
+
+ if (nonblock)
+ mode |= O_NONBLOCK;
+
sprintf(path, "per_cpu/cpu%d/trace_pipe_raw", cpu);
- tcpu->cpu = cpu;
- tcpu->fd = tracefs_instance_file_open(instance, path, mode);
- if (tcpu->fd < 0) {
- free(tcpu);
+ fd = tracefs_instance_file_open(instance, path, mode);
+ if (fd < 0)
return NULL;
- }
tep = tep_alloc();
if (!tep)
@@ -93,29 +136,18 @@ tracefs_cpu_open(struct tracefs_instance *instance, int cpu, bool nonblock)
if (ret < 0)
goto fail;
- tcpu->subbuf_size = tep_get_sub_buffer_size(tep);
+ subbuf_size = tep_get_sub_buffer_size(tep);
tep_free(tep);
tep = NULL;
- if (tcpu->flags & TC_NONBLOCK) {
- tcpu->ctrl_pipe[0] = -1;
- tcpu->ctrl_pipe[1] = -1;
- } else {
- /* ctrl_pipe is used to break out of blocked reads */
- ret = pipe(tcpu->ctrl_pipe);
- if (ret < 0)
- goto fail;
- if (tcpu->ctrl_pipe[0] > tcpu->fd)
- tcpu->nfds = tcpu->ctrl_pipe[0] + 1;
- else
- tcpu->nfds = tcpu->fd + 1;
- }
+ tcpu = tracefs_cpu_alloc_fd(fd, subbuf_size, nonblock);
+ if (!tcpu)
+ goto fail;
return tcpu;
fail:
tep_free(tep);
- close(tcpu->fd);
- free(tcpu);
+ close(fd);
return NULL;
}
@@ -126,6 +158,23 @@ static void close_fd(int fd)
close(fd);
}
+/**
+ * tracefs_cpu_free_fd - clean up the tracefs_cpu descriptor
+ * @tcpu: The descriptor created with tracefs_cpu_alloc_fd()
+ *
+ * Closes all the internal file descriptors that were opened by
+ * tracefs_cpu_alloc_fd(), and frees the descriptor.
+ */
+void tracefs_cpu_free_fd(struct tracefs_cpu *tcpu)
+{
+ close_fd(tcpu->ctrl_pipe[0]);
+ close_fd(tcpu->ctrl_pipe[1]);
+ close_fd(tcpu->splice_pipe[0]);
+ close_fd(tcpu->splice_pipe[1]);
+
+ free(tcpu);
+}
+
/**
* tracefs_cpu_close - clean up and close a raw trace descriptor
* @tcpu: The descriptor created with tracefs_cpu_open()
@@ -139,12 +188,7 @@ void tracefs_cpu_close(struct tracefs_cpu *tcpu)
return;
close(tcpu->fd);
- close_fd(tcpu->ctrl_pipe[0]);
- close_fd(tcpu->ctrl_pipe[1]);
- close_fd(tcpu->splice_pipe[0]);
- close_fd(tcpu->splice_pipe[1]);
-
- free(tcpu);
+ tracefs_cpu_free_fd(tcpu);
}
/**
--
2.35.1
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