| Message ID | 20180202145634.200291-1-arnd@arndb.de |
|---|---|
| State | Accepted |
| Commit | ebfc15019cfa72496c674ffcb0b8ef10790dcddc |
| Headers | show |
| Series | x86 bugfixes for LTO | expand |
On Fri, Feb 2, 2018 at 11:36 PM, tip-bot for Arnd Bergmann <tipbot@zytor.com> wrote: > Commit-ID: ebfc15019cfa72496c674ffcb0b8ef10790dcddc > Gitweb: https://git.kernel.org/tip/ebfc15019cfa72496c674ffcb0b8ef10790dcddc > Author: Arnd Bergmann <arnd@arndb.de> > AuthorDate: Fri, 2 Feb 2018 15:56:17 +0100 > Committer: Thomas Gleixner <tglx@linutronix.de> > CommitDate: Fri, 2 Feb 2018 23:33:50 +0100 > > x86/dumpstack: Avoid uninitlized variable > > In some configurations, 'partial' does not get initialized, as shown by > this gcc-8 warning: > > arch/x86/kernel/dumpstack.c: In function 'show_trace_log_lvl': > arch/x86/kernel/dumpstack.c:156:4: error: 'partial' may be used uninitialized in this function [-Werror=maybe-uninitialized] > show_regs_if_on_stack(&stack_info, regs, partial); > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > This initializes it to false, to get the previous behavior in this case. > > Fixes: a9cdbe72c4e8 ("x86/dumpstack: Fix partial register dumps") I just noticed my annotation got lost when I sent the patch. I originally meant to ask Josh to double-check whether it should be 'false' or 'true' here, or if we maybe need a larger change. Josh, could you take a look? Unfortunately I did not really understand your original commit, so I don't know what the safe choice is here in those cases in which 'partial' is uninitialized. Arnd
On Mon, Feb 05, 2018 at 10:21:06PM +0100, Arnd Bergmann wrote: > On Fri, Feb 2, 2018 at 11:36 PM, tip-bot for Arnd Bergmann > <tipbot@zytor.com> wrote: > > Commit-ID: ebfc15019cfa72496c674ffcb0b8ef10790dcddc > > Gitweb: https://git.kernel.org/tip/ebfc15019cfa72496c674ffcb0b8ef10790dcddc > > Author: Arnd Bergmann <arnd@arndb.de> > > AuthorDate: Fri, 2 Feb 2018 15:56:17 +0100 > > Committer: Thomas Gleixner <tglx@linutronix.de> > > CommitDate: Fri, 2 Feb 2018 23:33:50 +0100 > > > > x86/dumpstack: Avoid uninitlized variable > > > > In some configurations, 'partial' does not get initialized, as shown by > > this gcc-8 warning: > > > > arch/x86/kernel/dumpstack.c: In function 'show_trace_log_lvl': > > arch/x86/kernel/dumpstack.c:156:4: error: 'partial' may be used uninitialized in this function [-Werror=maybe-uninitialized] > > show_regs_if_on_stack(&stack_info, regs, partial); > > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > > > This initializes it to false, to get the previous behavior in this case. > > > > Fixes: a9cdbe72c4e8 ("x86/dumpstack: Fix partial register dumps") > > > I just noticed my annotation got lost when I sent the patch. I originally > meant to ask Josh to double-check whether it should be 'false' or 'true' > here, or if we maybe need a larger change. > > Josh, could you take a look? Unfortunately I did not really understand > your original commit, so I don't know what the safe choice is here > in those cases in which 'partial' is uninitialized. I think it doesn't matter, it seems to be a false positive warning. The 'partial' variable is only used when 'regs' is non-NULL, and 'regs' is only set in unwind_get_entry_regs() after 'partial' gets initialized. -- Josh
On Mon, Feb 5, 2018 at 10:39 PM, Josh Poimboeuf <jpoimboe@redhat.com> wrote: > On Mon, Feb 05, 2018 at 10:21:06PM +0100, Arnd Bergmann wrote: >> On Fri, Feb 2, 2018 at 11:36 PM, tip-bot for Arnd Bergmann >> <tipbot@zytor.com> wrote: >> > Commit-ID: ebfc15019cfa72496c674ffcb0b8ef10790dcddc >> > Gitweb: https://git.kernel.org/tip/ebfc15019cfa72496c674ffcb0b8ef10790dcddc >> > Author: Arnd Bergmann <arnd@arndb.de> >> > AuthorDate: Fri, 2 Feb 2018 15:56:17 +0100 >> > Committer: Thomas Gleixner <tglx@linutronix.de> >> > CommitDate: Fri, 2 Feb 2018 23:33:50 +0100 >> > >> > x86/dumpstack: Avoid uninitlized variable >> > >> > In some configurations, 'partial' does not get initialized, as shown by >> > this gcc-8 warning: >> > >> > arch/x86/kernel/dumpstack.c: In function 'show_trace_log_lvl': >> > arch/x86/kernel/dumpstack.c:156:4: error: 'partial' may be used uninitialized in this function [-Werror=maybe-uninitialized] >> > show_regs_if_on_stack(&stack_info, regs, partial); >> > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> > >> > This initializes it to false, to get the previous behavior in this case. >> > >> > Fixes: a9cdbe72c4e8 ("x86/dumpstack: Fix partial register dumps") >> >> >> I just noticed my annotation got lost when I sent the patch. I originally >> meant to ask Josh to double-check whether it should be 'false' or 'true' >> here, or if we maybe need a larger change. >> >> Josh, could you take a look? Unfortunately I did not really understand >> your original commit, so I don't know what the safe choice is here >> in those cases in which 'partial' is uninitialized. > > I think it doesn't matter, it seems to be a false positive warning. > > The 'partial' variable is only used when 'regs' is non-NULL, and 'regs' > is only set in unwind_get_entry_regs() after 'partial' gets initialized. Right, got it now. So my patch is correct either way, just the description could have been better. Arnd
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index afbecff161d1..a2d8a3908670 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -109,7 +109,7 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs, struct stack_info stack_info = {0}; unsigned long visit_mask = 0; int graph_idx = 0; - bool partial; + bool partial = false; printk("%sCall Trace:\n", log_lvl);
In some configurations, 'partial' does not get initialized, as shown by this gcc-8 warning: arch/x86/kernel/dumpstack.c: In function 'show_trace_log_lvl': arch/x86/kernel/dumpstack.c:156:4: error: 'partial' may be used uninitialized in this function [-Werror=maybe-uninitialized] show_regs_if_on_stack(&stack_info, regs, partial); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ This initializes it to false, to get the previous behavior in this case. a9cdbe72c4e8 ("x86/dumpstack: Fix partial register dumps") Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- arch/x86/kernel/dumpstack.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) -- 2.9.0