[lwip-devel] [bug #34429] In RAW/NO_SYS mode, with LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT set to 1, memory gets corrupted

[Min Xu]

Follow-up Comment #3, bug #34429 (project lwip):

My change that seem to work:
1: Adding break; after setting local_mem_free_count to 1 if mem_free_count is
non-zero.  No need to LOAD-STORE if a single STORE instruction suffices

2: Remove the extraneous LWIP_MEM_ALLOC_UNPROTECT() and
LWIP_MEM_ALLOC_PROTECT() when mem == lfree  ..  We don't want another
mem_malloc or mem_free to mess up the lfree

Section 1:
    for (ptr = (mem_size_t)((u8_t *)lfree - ram); ptr < MEM_SIZE_ALIGNED -
size;
         ptr = ((struct mem *)(void *)&ram[ptr])->next) {
      mem = (struct mem *)(void *)&ram[ptr];
#if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT
      mem_free_count = 0;
      LWIP_MEM_ALLOC_UNPROTECT();
      /* allow mem_free to run */
      LWIP_MEM_ALLOC_PROTECT();
      if (mem_free_count != 0) {
        local_mem_free_count = 1;
        break;
      }
      mem_free_count = 0;
#endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */


Section 2:
        if (mem == lfree) {
          /* Find next free block after mem and update lowest free pointer */
          while (lfree->used && lfree != ram_end) {
//            LWIP_MEM_ALLOC_UNPROTECT();
            /* prevent high interrupt latency... */
//            LWIP_MEM_ALLOC_PROTECT();
            lfree = (struct mem *)(void *)&ram[lfree->next];
          }
          LWIP_ASSERT("mem_malloc: !lfree->used", ((lfree == ram_end) ||
(!lfree->used)));
        }



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