I've been making --enable-thread-safety (USE_LOCKS) more viable by fixing deadlocks throughout the libelf library. This has required minimal code changes so far. However, I've hit a snag where "__elf64_updatenull_wrlock" calls "elf64_getchdr," which leads to "elf64_getshdr." This sequence attempts to acquire a read lock under a write lock and fails. Similarly, "elf64_getchdr" calls "elf_getdata," which also tries and fails to implement a read lock.
Unfortunately, fixing this particular deadlock requires more than minimal code changes. From what I understand, I may have a few options on how to fix this: 1) Create copies of the getchdr and elf_getdata functions, renaming them getchdr_wrlock and elf_getdata_wrlock. However, multiple copies of these functions could bloat the code, which may not be ideal. 2) Some type of write lock flag to indicate when a write lock is active. Either within the locking macro in eu-config.h or passed as an argument in the functions. Ultimately, I thought others may want to look into this to see if there might be options for a better solution. Here is the backtrace: Program received signal SIGABRT, Aborted. 0x00007ffff7837aff in raise () from /lib64/libc.so.6 #0 0x00007ffff7837aff in raise () from /lib64/libc.so.6 #1 0x00007ffff780aea5 in abort () from /lib64/libc.so.6 #2 0x00007ffff780ad79 in __assert_fail_base.cold.0 () from /lib64/libc.so.6 #3 0x00007ffff78304c9 in __assert_perror_fail () from /lib64/libc.so.6 #4 0x00007ffff7fda554 in elf64_getshdr (scn=0x40fc20) at ../../libelf/elf32_getshdr.c:292 #5 0x00007ffff7fe9590 in elf64_getchdr (scn=0x40fc20) at ../../libelf/elf32_getchdr.c:45 #6 0x00007ffff7fdf690 in __elf64_updatenull_wrlock (elf=0x40d880, change_bop=0x7fffffffac60, shnum=30) at ../../libelf/elf32_updatenull.c:407 #7 0x00007ffff7fdd83d in elf_update (elf=0x40d880, cmd=ELF_C_WRITE) at ../../libelf/elf_update.c:211 #8 0x0000000000405d9e in process_file (fname=0x7fffffffbb96 "testfile-s390x-hash-both") at ../../src/elfcompress.c:1336 #9 0x0000000000406232 in main (argc=7, argv=0x7fffffffb768) at ../../src/elfcompress.c:1458
