error : QProcessPrivate::createPipe: Cannot create pipe 0x2ed031ac: Too many open files

SGaist

Why not use QSerialPort ?

In any case, I don't see any call to close the file descriptor after use.

sachin786

@SGaist ok i will check that file and get back to u...and i am using QT creator 4.8.5 and in that there is no proper documentation for Qserialport thats why i am using normal serial port terminal available in ubuntu 12.04.

SGaist

You'll have to build the module yourself (there's a Qt 4 dedicated branch) but otherwise. The documentation is the same.

sachin786

@SGaist :: as far now problem is get fixed and my application running fine. as you help me to point out i am not closing file descriptor, i fix this by simply closing file descriptor and keeping track that no device peripheral left open more than once, at the moment i am using with regular serial port communication, thanx for all your suggestion it really help me alot.
once i finish this application surely i will try to work with QSerialPort :) Thank you once again and have great day ☺

sachin786

hello @SGaist ...following issue is occured while running the application and by this the finger print module get off

Unable to handle kernel NULL pointer dereference at virtual address 000000d4
pgd = 80004000
[000000d4] *pgd=00000000
Internal error: Oops: 17 [#1] PREEMPT SMP
Modules linked in:
CPU: 2    Not tainted  (3.0.35-2666-gbdde708 #26)
PC is at bus_freq_update+0x80/0x1d0
LR is at bus_freq_update+0x14/0x1d0
pc : [<8007129c>]    lr : [<80071230>]    psr: 60000013
sp : bfd43e80  ip : 00000001  fp : 0011edd8
r10: 00000000  r9 : 0011edd8  r8 : 80af7a54
r7 : 000e7ef0  r6 : 000000bc  r5 : 00000000  r4 : 80aaf958
r3 : ba1e0ae0  r2 : bfd43e78  r1 : 00000000  r0 : 80aabbfc
Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment kernel
Control: 10c53c7d  Table: 4faf404a  DAC: 00000015
Process kworker/2:1 (pid: 1386, stack limit = 0xbfd422f0)
Stack: (0xbfd43e80 to 0xbfd44000)
3e80: 80af778c 3b5dc100 001312d0 8008657c 001312d0 001312d0 80af7788 80af77783ea0: 80af7a54 bf9ff240 80af7a54 00000004 00000004 80aa7ac4 179a7b00 bfd43ee4
3ec0: 80537fdc 800868bc bfd43f04 800b4dc4 8c018f40 00000000 bfd43f8c 80533958
3ee0: 00000000 00000003 000f32a0 00060ae0 ffffff01 00000000 00000000 00000000
3f00: 00000000 00000002 8005af40 80aa7abc 80aa7abc 00000000 80aa7b00 80aa7cc0
3f20: 8005ad90 8c008d90 8005ad90 8039e698 00060ae0 803a2eac 00000001 bfa03e00
3f40: 8c0182e0 8c01e800 bfd42000 00000000 8c01e805 803a2d90 80b18474 800aab34
3f60: bfa03e10 00000001 bfa03e10 bfa03e00 8c0182e0 8c0182e8 bfa03e10 bfd42000
3f80: 8005b400 8005b400 00000009 800ab36c 00000013 00000000 8005b400 8005b400
3fa0: bfd43fc4 bffb1f00 bfa03e00 800ab1fc 00000013 00000000 00000000 00000000
3fc0: 00000000 800af80c 80062aa4 00000000 bfa03e00 00000000 00000000 00000000
3fe0: bfd43fe0 bfd43fe0 bffb1f00 800af78c 80062aa4 80062aa4 00000000 00000000
[<8007129c>] (bus_freq_update+0x80/0x1d0) from [<8008657c>] (set_cpu_freq+0x1b8/0x3a0)
[<8008657c>] (set_cpu_freq+0x1b8/0x3a0) from [<800868bc>] (mxc_set_target+0x10c/0x2bc)
[<800868bc>] (mxc_set_target+0x10c/0x2bc) from [<8039e698>] (__cpufreq_driver_target+0x50/0x64)
[<8039e698>] (__cpufreq_driver_target+0x50/0x64) from [<803a2eac>] (cpufreq_interactive_freq_down+0x11c/0x14c)
[<803a2eac>] (cpufreq_interactive_freq_down+0x11c/0x14c) from [<800aab34>] (process_one_work+0x10c/0x38c)
[<800aab34>] (process_one_work+0x10c/0x38c) from [<800ab36c>] (worker_thread+0x170/0x37c)
[<800ab36c>] (worker_thread+0x170/0x37c) from [<800af80c>] (kthread+0x80/0x88)
[<800af80c>] (kthread+0x80/0x88) from [<80062aa4>] (kernel_thread_exit+0x0/0x8)
Code: 0a00000d ebfffea0 ea00000b e5df6148 (e5963018) 
---[ end trace 8c5e7d506d5614d2 ]---
Unable to handle kernel paging request at virtual address fffffffc
pgd = 80004000
[fffffffc] *pgd=4fffe821, *pte=00000000, *ppte=00000000
Internal error: Oops: 17 [#2] PREEMPT SMP
Modules linked in:
CPU: 2    Tainted: G      D      (3.0.35-2666-gbdde708 #26)
PC is at kthread_data+0x4/0xc
LR is at wq_worker_sleeping+0xc/0xec
pc : [<800af9cc>]    lr : [<800abeec>]    psr: 00000193
sp : bfd43b98  ip : 8c018f90  fp : bfd43c4c
r10: ba1e0bfc  r9 : ba1e0bfc  r8 : ba1e0c78
r7 : 00000002  r6 : bfd42000  r5 : ba1e0ae0  r4 : 00000002
r3 : 00000000  r2 : 00000000  r1 : 00000002  r0 : ba1e0ae0
Flags: nzcv  IRQs off  FIQs on  Mode SVC_32  ISA ARM  Segment user
Control: 10c53c7d  Table: 4faf404a  DAC: 00000015
Process kworker/2:1 (pid: 1386, stack limit = 0xbfd422f0)
Stack: (0xbfd43b98 to 0xbfd44000)
3b80:                                                       8c018f40 80533a6c
3ba0: 809d8c68 80126fe4 bfd43bcf 00000001 bfa03ed0 bffc31e0 0000056a 8015754c
3bc0: 00000000 00000000 8005af40 8005af40 8005a1b4 8005af40 c01dfaab 00000000
3be0: c01dfaab 800980f8 ba230000 ba1e0ae0 bfc08000 ba230504 80af8298 ba230000
3c00: 00000000 8005a260 ba1e0ae0 8009810c ba1e0ae0 8005a260 8007129e 800da9d4
3c20: 00000000 00000000 bfd43c28 ba1e0ae0 ffffffff ba1e0ad8 bff8c000 ba1e0bfc
3c40: ba1e0bfc ba1e0bfc 809d1bc8 80099390 00000000 bfd43c64 bfd42000 00000001
3c60: 80abd4bc bfd43c64 bfd43c64 ba1e0c44 8007129e bfd42000 00000000 00000001
3c80: 8007129e 00000000 800712a0 bfd43cda 809d1bc8 80065740 bfd422f0 0000000b
3ca0: 00000008 00000000 30000001 30303061 20643030 66666265 30616566 30616520
3cc0: 30303030 35652062 31366664 28203834 36393565 38313033 00002029 00000000
3ce0: 0011edd8 00000000 000000d4 00000017 bfd43e38 ba1e0ae0 00000017 00000000
3d00: 0011edd8 8052f84c bfd43e38 8006c488 00000000 00000001 00000200 bfd43de4
3d20: 00591ec2 00000001 00000000 00000000 80a94080 80aa7aa0 bfd43dc4 80090764
3d40: 8c01825c bfd43de4 00000001 00000000 00000002 bfd42000 bfd43de4 8005af40
3d60: 00000000 8005af40 00000000 8008fe20 00000000 00000017 80aab428 000000d4
3d80: bfd43e38 80af7a54 20000113 00000000 0011edd8 8005c384 bffd1780 ffffffff
3da0: 8005af40 00000000 00000000 bffc1900 00000000 8005af40 00000000 00000000
3dc0: 001cbcc5 00000000 bffc1900 00000000 00000fff 00000000 00000000 00000000
3de0: 00000000 00000001 00000000 00000000 00000000 00000000 00000000 00000000
3e00: 00000000 00000000 00000000 bfe4fe00 00000000 bfe4fe00 00000040 800b4ef0
3e20: 00000000 0000040f 00000007 000000bc 000e7ef0 80061990 80aabbfc 00000000
3e40: bfd43e78 ba1e0ae0 80aaf958 00000000 000000bc 000e7ef0 80af7a54 0011edd8
3e60: 00000000 0011edd8 00000001 bfd43e80 80071230 8007129c 60000013 ffffffff
3e80: 80af778c 3b5dc100 001312d0 8008657c 001312d0 001312d0 80af7788 80af7778
3ea0: 80af7a54 bf9ff240 80af7a54 00000004 00000004 80aa7ac4 179a7b00 bfd43ee4
3ec0: 80537fdc 800868bc bfd43f04 800b4dc4 8c018f40 00000000 bfd43f8c 80533958
3ee0: 00000000 00000003 000f32a0 00060ae0 ffffff01 00000000 00000000 00000000
3f00: 00000000 00000002 8005af40 80aa7abc 80aa7abc 00000000 80aa7b00 80aa7cc0
3f20: 8005ad90 8c008d90 8005ad90 8039e698 00060ae0 803a2eac 00000001 bfa03e00
3f40: 8c0182e0 8c01e800 bfd42000 00000000 8c01e805 803a2d90 80b18474 800aab34
3f60: bfa03e10 00000001 bfa03e10 bfa03e00 8c0182e0 8c0182e8 bfa03e10 bfd42000
3f80: 8005b400 8005b400 00000009 800ab36c 00000013 00000000 8005b400 8005b400
3fa0: bfd43fc4 bffb1f00 bfa03e00 800ab1fc 00000013 00000000 00000000 00000000
3fc0: 00000000 800af80c 80062aa4 00000000 bfa03e00 00000001 00000000 00000000
3fe0: bfd43fe0 bfd43fe0 bffb1f00 800af78c 80062aa4 80062aa4 00000000 00000000
[<800af9cc>] (kthread_data+0x4/0xc) from [<800abeec>] (wq_worker_sleeping+0xc/0xec)
[<800abeec>] (wq_worker_sleeping+0xc/0xec) from [<80533a6c>] (__schedule+0x390/0x6c0)
[<80533a6c>] (__schedule+0x390/0x6c0) from [<80099390>] (do_exit+0x450/0x6e8)
[<80099390>] (do_exit+0x450/0x6e8) from [<80065740>] (die+0x228/0x284)
[<80065740>] (die+0x228/0x284) from [<8052f84c>] (__do_kernel_fault.part.4+0x54/0x74)
[<8052f84c>] (__do_kernel_fault.part.4+0x54/0x74) from [<8006c488>] (do_page_fault+0x2b4/0x31c)
[<8006c488>] (do_page_fault+0x2b4/0x31c) from [<8005c384>] (do_DataAbort+0x34/0x9c)
[<8005c384>] (do_DataAbort+0x34/0x9c) from [<80061990>] (__dabt_svc+0x70/0xa0)
Exception stack(0xbfd43e38 to 0xbfd43e80)
3e20:                                                       80aabbfc 00000000
3e40: bfd43e78 ba1e0ae0 80aaf958 00000000 000000bc 000e7ef0 80af7a54 0011edd8
3e60: 00000000 0011edd8 00000001 bfd43e80 80071230 8007129c 60000013 ffffffff
[<80061990>] (__dabt_svc+0x70/0xa0) from [<8007129c>] (bus_freq_update+0x80/0x1d0)
[<8007129c>] (bus_freq_update+0x80/0x1d0) from [<8008657c>] (set_cpu_freq+0x1b8/0x3a0)
[<8008657c>] (set_cpu_freq+0x1b8/0x3a0) from [<800868bc>] (mxc_set_target+0x10c/0x2bc)
[<800868bc>] (mxc_set_target+0x10c/0x2bc) from [<8039e698>] (__cpufreq_driver_target+0x50/0x64)
[<8039e698>] (__cpufreq_driver_target+0x50/0x64) from [<803a2eac>] (cpufreq_interactive_freq_down+0x11c/0x14c)
[<803a2eac>] (cpufreq_interactive_freq_down+0x11c/0x14c) from [<800aab34>] (process_one_work+0x10c/0x38c)
[<800aab34>] (process_one_work+0x10c/0x38c) from [<800ab36c>] (worker_thread+0x170/0x37c)
[<800ab36c>] (worker_thread+0x170/0x37c) from [<800af80c>] (kthread+0x80/0x88)
[<800af80c>] (kthread+0x80/0x88) from [<80062aa4>] (kernel_thread_exit+0x0/0x8)
Code: eaff9868 80537f4c 809db0fc e590316c (e5130004) 
\00\F0

after some time(2 to 3 hour) it shoots this error...

SGaist

There's a faulty module doing something wrong.

sachin786

the module is working properly for 4 hours or 5 hour then automatically turned off and in serial port terminal show above mention output...

SGaist

That doesn't mean it doesn't do something wrong. For example, a small memory (one byte) leak can take days until it eats all the system's memory but it still will.

sachin786

i can't figure out what is the issue related to it error...

SGaist

The driver used to talk with the device might be faulty.

sachin786

@SGaist i am not sure about this...for temporary solution i have to reboot my device after 3 hour.. ..