979138 - No way to add more Toplevel protocols after Nuwa's enable

Status: RESOLVED DUPLICATE of bug 910010

(Core :: IPC, defect)

Description

[Chiajung Hung [:chiajung]]

Since Nuwa will trigger a CloneToplevel IPC, which contains a Fd mapping array, and current toplevel are: PCompositor, PImageBridge, PContent, PBackground, which fits the fd limit in 1 IPC message, so it works.
However, for performance consideration, we are implementing a new top level protocol in Bug 959089, and it cause B2G crash endlessly.
By changing http://dxr.mozilla.org/mozilla-central/source/ipc/chromium/src/chrome/common/file_descriptor_set_posix.h#33 to 5, it does work quiet well.

Comment 1

[Cervantes Yu [:cyu] [:cervantes]]

The limit of 4 looks quite arbitrary. I don't see scm(3) or sendmsg(2) mentioning limitation of the number of file descriptors passed. I don't see any reason we can't increase the limit.

Comment 2

[Chiajung Hung [:chiajung]]

Attachment: patch

I think the limitation of 4 is a random pick.
Increase the limitation make it possible to add 1 more top level protocol, without much change.

Comment 3

[Ben Turner (not reading bugmail, use the needinfo flag!)]

Comment on attachment 8385141 [details] [diff] [review]
patch

Review of attachment 8385141 [details] [diff] [review]:
-----------------------------------------------------------------

This will just happen again the next time someone adds a new protocol, right? We should figure out a better way to do this IMO.

Comment 4

[Ben Turner (not reading bugmail, use the needinfo flag!)]

See bug 910010 also.

Comment 5

[Chiajung Hung [:chiajung]]

(In reply to ben turner [:bent] (use the needinfo? flag!) from comment #3)
> Comment on attachment 8385141 [details] [diff] [review]
> patch
> 
> Review of attachment 8385141 [details] [diff] [review]:
> -----------------------------------------------------------------
> 
> This will just happen again the next time someone adds a new protocol,
> right? We should figure out a better way to do this IMO.

Sure! Since I have no idea about how Nuwa work, and where triggers the IPC that pass fd, I can only workaround it here.

As bug 910010 seems the right way to do this, just mark this as duplicate.
Thanks for the infomation!