Merge branch 'adam-shmem'

Uplift shmem from wr-switch-sw repo. Signed-off-by: Adam Wujek <adam.wujek@cern.ch>

Merge branch 'adam-shmem'
Uplift shmem from wr-switch-sw repo. Signed-off-by: Adam Wujek <adam.wujek@cern.ch>
96a78e15 · Adam Wujek · ab7106d2 · d5e619c5 · 96a78e15 · 96a78e15
Commit 96a78e15 authored Sep 14, 2016 by Adam Wujek 💬
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Showing with 61 additions and 9 deletions

shmem.h arch-wrs/include/libwr/shmem.h +15 -2

wrs-msg.h arch-wrs/include/libwr/wrs-msg.h +16 -0

shmem.c arch-wrs/shmem.c +30 -7

No files found.
--- a/arch-wrs/include/libwr/shmem.h
+++ b/arch-wrs/include/libwr/shmem.h
@@ -32,7 +32,8 @@ struct wrs_shm_head {
 	int pid;		/* The current pid owning the area */

 	unsigned pidsequence;	/* Each new pid must increments this */
-	unsigned sequence;	/* If we need consistency, this is it */
+	unsigned sequence;	/* If we need consistency, this is it. LSB bit
+				 * informs whether shmem is locked already */
 	unsigned version;	/* Version of the data structure */
 	unsigned data_size;	/* Size of it (for binary dumps) */
 };
@@ -42,6 +43,14 @@ struct wrs_shm_head {
 #define WRS_SHM_WRITE  0x0001
 #define WRS_SHM_LOCKED 0x0002 /* at init time: writers locks, readers wait  */

+#define WRS_SHM_LOCK_MASK 0x0001
+
+/* return values of wrs_shm_get_and_check */
+#define WRS_SHM_OPEN_OK           0x0001
+#define WRS_SHM_OPEN_FAILED       0x0001
+#define WRS_SHM_WRONG_VERSION     0x0002
+#define WRS_SHM_INCONSISTENT_DATA 0x0003
+
 /* Set custom path for shmem */
 void wrs_shm_set_path(char *new_path);

@@ -69,7 +78,11 @@ void *wrs_shm_follow(void *headptr, void *ptr);
 /* Before and after writing a chunk of data, act on sequence and stamp */
 #define WRS_SHM_WRITE_BEGIN	1
 #define WRS_SHM_WRITE_END	0
-extern void wrs_shm_write(void *headptr, int flags);
+
+/* A helper to pass the name of caller function */
+#define wrs_shm_write(headptr, flags) wrs_shm_write_caller(headptr, flags, \
+							   __func__)
+extern void wrs_shm_write_caller(void *headptr, int flags, const char *caller);

 /* A reader can rely on the sequence number (in the <linux/seqlock.h> way) */
 extern unsigned wrs_shm_seqbegin(void *headptr);

--- a/arch-wrs/include/libwr/wrs-msg.h
+++ b/arch-wrs/include/libwr/wrs-msg.h
+/*
+ * File to provide printout interfaces used in libwr of wrs-switch-sw
+ */
+#ifndef __WRS_MSG_H__
+#define __WRS_MSG_H__
+
+#include <ppsi/ppsi.h>
+/* And shortands for people using autocompletion -- but not all levels */
+#define pr_error(...)	pp_error(__VA_ARGS__)
+#define pr_err(...)	pr_error(__VA_ARGS__)
+#define pr_warning(...)
+#define pr_warn(...)
+#define pr_info(...)
+#define pr_debug(...)
+
+#endif /* __WRS_MSG_H__ */
--- a/arch-wrs/shmem.c
+++ b/arch-wrs/shmem.c
@@ -12,6 +12,7 @@

 #include <libwr/shmem.h>
 #include <libwr/util.h>
+#include <libwr/wrs-msg.h>

 #define SHM_LOCK_TIMEOUT_MS 50 /* in ms */

@@ -140,25 +141,33 @@ int wrs_shm_put(void *headptr)
 /* Open shmem and check if data is available
 * return 0 when ok, otherwise error
 * 1 when openning shmem failed
- * 2 when version is 0 */
+ * 2 when version is 0
+ * 3 when data in shmem is inconsistent, function shall be called again
+ */
 int wrs_shm_get_and_check(enum wrs_shm_name shm_name,
 				 struct wrs_shm_head **head)
 {
 	int ii;
 	int version;
+	int ret;

 	/* try to open shmem */
 	if (!(*head) && !(*head = wrs_shm_get(shm_name, "",
 					WRS_SHM_READ | WRS_SHM_LOCKED))) {
-		return 1;
+		return WRS_SHM_OPEN_FAILED;
 	}

 	ii = wrs_shm_seqbegin(*head);
 	/* read head version */
 	version = (*head)->version;
-	if (wrs_shm_seqretry(*head, ii) || !version) {
-		/* data in shmem available and version not zero */
-		return 2;
+	ret = wrs_shm_seqretry(*head, ii);
+	if (ret) {
+		/* inconsistent data in shmem */
+		return WRS_SHM_INCONSISTENT_DATA;
+	}
+	if (!version) {
+		/* data in shmem available and version is zero */
+		return WRS_SHM_WRONG_VERSION;
 	}

 	/* all ok */
@@ -197,15 +206,29 @@ void *wrs_shm_follow(void *headptr, void *ptr)
 }

 /* Before and after writing a chunk of data, act on sequence and stamp */
-void wrs_shm_write(void *headptr, int flags)
+void wrs_shm_write_caller(void *headptr, int flags, const char *caller)
 {
 	struct wrs_shm_head *head = headptr;

+	head->sequence++;
+	pr_debug("caller: %s\n", caller);
+
 	if (flags == WRS_SHM_WRITE_END) {
 		/* At end-of-writing update the timestamp too */
 		head->stamp = get_monotonic_sec();
+		if (head->sequence & 1)
+			pr_error("On the shmem write end the sequence number "
+				 "(%d) is even (should be odd). The caller of"
+				 " wrs_shm_write is %s\n",
+				 head->sequence, caller);
+	} else {
+		if (!(head->sequence & 1))
+			pr_error("On the shmem write begin the sequence number"
+				 " (%d) is odd (should be even). The caller of"
+				 " wrs_shm_write is %s\n",
+				 head->sequence, caller);
 	}
-	head->sequence++;
+
 	return;
 }