(mynewt-core) branch master updated: fcb: Fix checks for empty fcb

[jerzy]

This is an automated email from the ASF dual-hosted git repository.

kasjer pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/mynewt-core.git


The following commit(s) were added to refs/heads/master by this push:
     new 8b0f0411b fcb: Fix checks for empty fcb
8b0f0411b is described below

commit 8b0f0411ba7e032b80108bf014cda3ca02ea1490
Author: Jerzy Kasenberg <jerzy.kasenb...@codecoup.pl>
AuthorDate: Thu May 21 12:34:08 2026 +0200

    fcb: Fix checks for empty fcb
    
    Functions fcb_is_empty_nolock and fcb_is_empty
    incorrectly reported that fcb sector was not empty
    for devices that have write alignment > 8.
    
    On devices with higher alignment that leads to
    infinite loop during fcb rotation where code
    could not detect that sector was already empty.
    
    Now code takes into account flash alignment when
    checks if oldest sector write offset.
    
    Signed-off-by: Jerzy Kasenberg <jerzy.kasenb...@codecoup.pl>
---
 fs/fcb/src/fcb.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/fs/fcb/src/fcb.c b/fs/fcb/src/fcb.c
index 1494f9a53..bc39e0616 100644
--- a/fs/fcb/src/fcb.c
+++ b/fs/fcb/src/fcb.c
@@ -23,6 +23,12 @@
 #include "fcb_priv.h"
 #include "string.h"
 
+static int
+fcb_start_offset(struct fcb *fcb)
+{
+    return fcb_len_in_flash(fcb, sizeof(struct fcb_disk_area));
+}
+
 int
 fcb_init(struct fcb *fcb)
 {
@@ -80,7 +86,7 @@ fcb_init(struct fcb *fcb)
     fcb->f_align = max_align;
     fcb->f_oldest = oldest_fap;
     fcb->f_active.fe_area = newest_fap;
-    fcb->f_active.fe_elem_off = fcb_len_in_flash(fcb, sizeof(struct 
fcb_disk_area));
+    fcb->f_active.fe_elem_off = fcb_start_offset(fcb);
     fcb->f_active_id = newest;
     fcb->f_active.fe_elem_ix = 0;
 
@@ -133,10 +139,11 @@ fcb_free_sector_cnt(struct fcb *fcb)
 int
 fcb_is_empty_nolock(struct fcb *fcb)
 {
-    bool ret = false;
+    bool ret;
+    uint32_t first_entry_offset = fcb_start_offset(fcb);
 
-    ret = (fcb->f_active.fe_area == fcb->f_oldest &&
-           fcb->f_active.fe_elem_off == sizeof(struct fcb_disk_area));
+    ret = fcb->f_active.fe_area == fcb->f_oldest &&
+          fcb->f_active.fe_elem_off == first_entry_offset;
 
     return ret;
 }
@@ -144,16 +151,17 @@ fcb_is_empty_nolock(struct fcb *fcb)
 int
 fcb_is_empty(struct fcb *fcb)
 {
-    int rc = 0;
-    bool ret = false;
+    int rc;
+    bool ret;
+    uint32_t first_entry_offset = fcb_start_offset(fcb);
 
     rc = os_mutex_pend(&fcb->f_mtx, OS_WAIT_FOREVER);
     if (rc && rc != OS_NOT_STARTED) {
         return FCB_ERR_ARGS;
     }
 
-    ret = (fcb->f_active.fe_area == fcb->f_oldest &&
-      fcb->f_active.fe_elem_off == sizeof(struct fcb_disk_area));
+    ret = fcb->f_active.fe_area == fcb->f_oldest &&
+          fcb->f_active.fe_elem_off == first_entry_offset;
 
     os_mutex_release(&fcb->f_mtx);