Messages in this thread | | | From | David Howells <> | Subject | Re: [PATCH 3/4] coredump: ELF-FDPIC: enable to omit anonymous shared memory | Date | Tue, 20 Feb 2007 10:58:17 +0000 |
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Kawai, Hidehiro <hidehiro.kawai.ez@hitachi.com> wrote:
> Core dumping is separated two phases, one is the phase of writing > headers, the other is the phase of writing memory segments. If the > coredump_omit_anon_shared setting is changed between these two phases, > a corrupted core file will be generated because the offsets written > in headers don't match their bodies. So we need to use the same > setting in both phases.
Hmmm... Okay.
> I think that locking makes codes complex and generates overhead. > So I wouldn't like to use lock as far as possible. I think passing > the flag as an extra argument is the simplest implementation to > avoid the core file corruption.
Actually, I don't think the locking is that hard or that complex.
int do_coredump(long signr, int exit_code, struct pt_regs * regs) { <setup vars>
down_read(&coredump_settings_sem);
...
fail: up_read(&coredump_settings_sem); return retval; }
And:
static ssize_t proc_coredump_omit_anon_shared_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { <setup vars>
down_write(&coredump_settings_sem);
...
out_no_task: up_write(&coredump_settings_sem); return ret; }
The same could be applied to all controls that change the coredumping variables, in particular the sysctl for core_pattern could be wrapped so as to remove one of the reliances on lock_kernel() and the lock_kernel pair could be removed from do_coredump().
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