Re: [Crash-utility] [PATCH 1/1] Resend CLI list command, print deep structure members
----- Original Message -----
Hi Dave,
my bad.
Since you've made some simplifications in my patch, I hope it's ok to make
short patch.
Hi Alex,
I've run into three problems dealing with embedded arrays.
First, should array elements inside an embedded structure be
selectable? For example, the task_struct has an embedded
task_rss_stat structure:
crash> task_struct.rss_stat
struct task_struct {
[456] struct task_rss_stat rss_stat;
}
that contains a "count" array:
crash> task_rss_stat
struct task_rss_stat {
int events;
int count[3];
}
SIZE: 16
I can display the whole thing:
crash> task -R rss_stat
PID: 11722 TASK: ffff8801073da5d0 CPU: 0 COMMAND: "crash"
rss_stat = {
events = 11,
count = {0, 0, 0}
},
Or break it down into its two members, individually or both at the same time:
crash> task -R rss_stat.events
PID: 11722 TASK: ffff8801073da5d0 CPU: 1 COMMAND: "crash"
rss_stat.events = 13,
crash> task -R rss_stat.count
PID: 11722 TASK: ffff8801073da5d0 CPU: 1 COMMAND: "crash"
rss_stat.count = {0, 0, 0}
crash> task -R rss_stat.events,rss_stat.count
PID: 11722 TASK: ffff8801073da5d0 CPU: 1 COMMAND: "crash"
rss_stat.events = 14,
rss_stat.count = {0, 0, 0}
But trying to access a member of the rss_stat.count[] array fails:
crash> task -R rss_stat.count[1]
PID: 11722 TASK: ffff8801073da5d0 CPU: 2 COMMAND: "crash"
task: invalid structure member reference: rss_stat.count[1]
crash>
Is that expected behavior?
Secondly, on a somewhat related note, this seems strange. The
task_struct has an embedded array of 3 pid_link structures:
crash> task_struct.pids
struct task_struct {
[608] struct pid_link pids[3];
}
Here they are all dumped:
crash> task -R pids
PID: 11722 TASK: ffff8801073da5d0 CPU: 2 COMMAND: "crash"
pids = {{
node = {
next = 0x0,
pprev = 0xffff880105fc9888
},
pid = 0xffff880105fc9880
}, {
node = {
next = 0xffff880209d01198,
pprev = 0xffff880209d05d38
},
pid = 0xffff88000eeefd00
}, {
node = {
next = 0xffff880209d011b0,
pprev = 0xffff880209d05d50
},
pid = 0xffff88010d07ed00
}},
Or I can pick just one member of the array:
crash> task -R pids[1]
PID: 11722 TASK: ffff8801073da5d0 CPU: 0 COMMAND: "crash"
pids[1] = {
node = {
next = 0xffff880209d01198,
pprev = 0xffff880209d02848
},
pid = 0xffff88000eeefd00
},
And refine it further by asking for just the "node" member:
crash> task -R pids[1].node
PID: 11722 TASK: ffff8801073da5d0 CPU: 0 COMMAND: "crash"
pids[1].node = {
next = 0xffff880209d01198,
pprev = 0xffff880209d02848
},
But for some reason, it fails to accept the "pid_link.pid" member:
crash> task -R pids[1].pid
PID: 11722 TASK: ffff8801073da5d0 CPU: 0 COMMAND: "crash"
task: invalid structure member reference: pids[1].pid
And third, this behavior also doesn't seem correct. Here again I select
just the first element of the task_struct.pids[] array:
crash> task -R pids[0].node
PID: 11722 TASK: ffff8801073da5d0 CPU: 2 COMMAND: "crash"
pids[0].node = {
next = 0x0,
pprev = 0xffff880105fc9888
},
But it allows me to leave off the "pids[x]" reference, and if so, it defaults
to the first member of the array:
crash> task -R pids.node
PID: 11722 TASK: ffff8801073da5d0 CPU: 0 COMMAND: "crash"
pids.node = {
next = 0x0,
pprev = 0xffff880105fc9888
},
Should it reject that syntax?
Dave