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ba39486d2c
[Changes from V1:
- The __compat_break has been abandoned in favor of
a more readable can_loop macro that can be used anywhere, including
loop conditions.]
The macro list_for_each_entry is defined in bpf_arena_list.h as
follows:
#define list_for_each_entry(pos, head, member) \
for (void * ___tmp = (pos = list_entry_safe((head)->first, \
typeof(*(pos)), member), \
(void *)0); \
pos && ({ ___tmp = (void *)pos->member.next; 1; }); \
cond_break, \
pos = list_entry_safe((void __arena *)___tmp, typeof(*(pos)), member))
The macro cond_break, in turn, expands to a statement expression that
contains a `break' statement. Compound statement expressions, and the
subsequent ability of placing statements in the header of a `for'
loop, are GNU extensions.
Unfortunately, clang implements this GNU extension differently than
GCC:
- In GCC the `break' statement is bound to the containing "breakable"
context in which the defining `for' appears. If there is no such
context, GCC emits a warning: break statement without enclosing `for'
o `switch' statement.
- In clang the `break' statement is bound to the defining `for'. If
the defining `for' is itself inside some breakable construct, then
clang emits a -Wgcc-compat warning.
This patch adds a new macro can_loop to bpf_experimental, that
implements the same logic than cond_break but evaluates to a boolean
expression. The patch also changes all the current instances of usage
of cond_break withing the header of loop accordingly.
Tested in bpf-next master.
No regressions.
Signed-off-by: Jose E. Marchesi <jose.marchesi@oracle.com>
Cc: david.faust@oracle.com
Cc: cupertino.miranda@oracle.com
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Link: https://lore.kernel.org/r/20240511212243.23477-1-jose.marchesi@oracle.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.