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| author | Florian Weimer <fweimer@redhat.com> | 2020-05-20 15:40:35 +0200 |
|---|---|---|
| committer | Florian Weimer <fweimer@redhat.com> | 2020-07-06 11:15:58 +0200 |
| commit | 706ad1e7af37be1d25fc2359bda006d31fe0d11b (patch) | |
| tree | d06e6a96c1d319a1d27fa6b6e87cfadf8bd6ef08 /elf/libc_early_init.c | |
| parent | 8f4632deb3545b2949cec5454afc3cb21a0024ea (diff) | |
| download | glibc-706ad1e7af37be1d25fc2359bda006d31fe0d11b.zip glibc-706ad1e7af37be1d25fc2359bda006d31fe0d11b.tar.gz glibc-706ad1e7af37be1d25fc2359bda006d31fe0d11b.tar.bz2 | |
Add the __libc_single_threaded variable
The variable is placed in libc.so, and it can be true only in
an outer libc, not libcs loaded via dlmopen or static dlopen.
Since thread creation from inner namespaces does not work,
pthread_create can update __libc_single_threaded directly.
Using __libc_early_init and its initial flag, implementation of this
variable is very straightforward. A future version may reset the flag
during fork (but not in an inner namespace), or after joining all
threads except one.
Reviewed-by: DJ Delorie <dj@redhat.com>
Diffstat (limited to 'elf/libc_early_init.c')
| -rw-r--r-- | elf/libc_early_init.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/elf/libc_early_init.c b/elf/libc_early_init.c index f0fcf64..86da66d 100644 --- a/elf/libc_early_init.c +++ b/elf/libc_early_init.c @@ -19,13 +19,18 @@ #include <ctype.h> #include <libc-early-init.h> #include <rseq-internal.h> +#include <sys/single_threaded.h> void __libc_early_init (_Bool initial) { /* Initialize ctype data. */ __ctype_init (); + /* Register rseq ABI to the kernel for the main program's libc. */ if (initial) rseq_register_current_thread (); + + /* Only the outer namespace is marked as single-threaded. */ + __libc_single_threaded = initial; } |